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LIGHT: 



ITS INFLUENCE 



ON LIFE AND HEALTH. 



FORBES WINSLOW, M.D., 

D.C.L. Oxon. (Hon.), 
&c. &c. 




LONDON: 

LONGMANS, GREEN, READER, & DYER. 

1867. 



TO 



SIR WILLIAM FEKGUSSON, Bart., P.E.S. 

Fellow and Member of the Council of the Royal College of Surgeons, England ; 
Surgeon and Professor of Surgery at King's College, Hospital ; Surgeon Extraor- 
dinary to Her Majesty the Queen ; and Surgeon in Ordinary to His late Royal 
Highness the Prince Consort ; late Professor of Human Anatomy and Surgery 
R.C.S. Eng., and Examiner on Surgery at the University of London, 



}i& Work is Jjebitateb-, 

BY THE AUTHOR, 



AS A TRIFLING MARK OF ADMIRATION AND RESPECT 

FOR 

HIS DISTINGUISHED TALENTS AND BRILLIANT ATTAINMENTS, 

AND 

IN PLEASING REMEMBRANCE 

OF AN UNINTERRUPTED FRIENDSHIP OF TWENTY-SEVEN 
YEARS. 



PREFACE. 



The object of this work is to demonstrate 
the inestimable value of light as an hygienic 
agent, and to analytically examine its phy-. 
siological influence in the development of 
vital phenomena as manifested in the 
animal and vegetable kingdoms. 

How impossible it is to exaggerate the 
amount of blessing which flows from the 
action of the sun, that 

" Great source of day, for ever pouring wide ' 
From world to world the vital ocean round" 

not only on organic, but inorganic matter. 

Deprived of its life-generating and health- 
sustaining power, the whole of animated 



vi Preface. 

nature would be a sterile blank, and man, the 
highest order of intelligent beings, become 
blighted in mind and degenerated in body. 

In the composition of this volume I 
have been under the necessity of levying 
contributions on the writings of established 
physicists. 

I lay no claim to original experimental 
research, but desire only to be considered 
as a wanderer on the vast shore of science, 
picking up here rare shells, there valuable 
pebbles, and then classifying them, with 
the view of illustrating a branch of inquiry 
of deep philosophical interest. 

It is impossible to contemplate the facts 
scattered through the following pages with- 
out being solemnly impressed with a sense 
of man's deep obligation to God, — the Source 
of all true Light, — for thus beneficently 



Preface. vii 

surrounding our planet by an influence so 
pre-eminently conducive to the health and 
happiness of the human race.* 



Cavendish Square, London, 
April, 1867. 



* A portion of the chapter on the " Lunar Ray" appeared 
many years ago in a paper of my own, on " Lucid Intervals," 
published in the Psychological Journal. 



TABLE OF CONTENTS, 



PART I. 

THE SOLAR-BEAM. 

Origin of light, i ; Healthful and morbid effects of light 
upon the animal and vegetable kingdom, 2 ; No vi- 
tality or healthful structure without light, 4 ; * Solar- 
air-bath" of the ancients, 4 ; Bodily deformities , crime, 
and mental disease produced by darkness, 5 ; Health 
of those who live in the country as compared with the 
inhabitants of manufacturing towns, 7 ; The absence 
of light on miners and colliers, 7; Diseases caused 
by the absence of light, 8 ; Unhealthy condition of 
those who labour by night and sleep by day, 9 ; Deep 
mining at Geelong, 10; Development of children re- 
tarded by working in mines, 1 1 ; Stunted forms ob- 
served among the miners of Chimay, 12 ; Effects of 
dampness and deficient nourishment viewed in con- 
nexion with want of light, 13; Influence of light upon 
animals, 14 ; Arrest of animal development, 15 ; Blind- 
ness of fish caused by want of light, 17-19; Dis- 
colouration of different races of men caused by solar 
heat, 20 ; The brown skins of the natives of Lapland and 



Contents. 



Greenland, 2 1 ; White skins of negroes dwelling in the 
forests, 22 ; Black colour contrasted with that of red 
or olive negroes, 22 ; Black, white, and spotted 
negroes, 23 ; Effect of food on the hair, 24 ; 
Complexions of intemperate persons, 24; Red In- 
dians turned white, 25; Influence of the sun in 
tropical climates, 26 ; Albinos of the torrid zone, 27 ; 
fish of great oceanic depths, 27 ; Effect of the absence 
of light on the women of the seraglio, 28 ; Statures of 
different races of men, 29-31 ; Mental condition of the 
Arabs, 33 ; Inhabitants of high latitudes possess su- 
perior muscular force, 34; Northern countries more 
favourable than southern to longevity, 34 ; Influence 
of climate upon physical and mental organization, 36 ; 
Effect of deep sea-water on vegetable and animal life, 
37 ; The depth of the ocean, 38-41 ; Depth at which 
solar light penetrates, 41 ; Temperature of the ocean, 
42 ; Different colours of the sea, 44 ; Causes of the 
varied tints of the sea, 45 ; Distribution of animal 
life in the sea, 46 ; Classification of marine animals, 
47 ; Microscopic shells found in deep sea deposit, 48 ; 
Animal and vegetable life incompatible with certain 
altitudes and depths, 50; Amount of pressure at 
certain oceanic depths, 51-53 ; Tendency of plants to 
follow light, 53 ; Plants and animals nurtured in dark- 
ness altered in colour, 56 ; Animal and vegetable sub- 
stances near the surface of the sea brilliantly coloured, 
59 ; Brilliant colours of animals and plants in the 
tropics, 60 ; Action of light necessary for development 
of vegetable colours, 63 ; Physiological influence of 



Contents, xi 



light on the colour of plants, 64 ; A definite quantity 
of heat required for development of plants, 64 ; Insect 
life, 70-74 ; Chemical influence of light on certain 
drugs, 74-77 ; Effect of light passing through dif- 
ferent coloured media on the germination of plants, 
78-81 ; Metals discovered in the solar beam by 
the spectroscope, a Fraunhofer's lines," 82-86 ; Dis- 
eases caused by exposure to intense solar heat, 87. 



PART II. 
THE LUNAR-RAY. 

Opinions of the ancients as to the influence of the moon, 
89-97 ; Different parts of the body under planetary 
influence, 97 ; The moon's power in causing tidal 
action, 101 ; Belief of Spaniards and West India 
negroes that the sick always die at ebb-tide, 102 ; 
Principal authorities in support of the theory of pla- 
netary influence, 107-112; Drs. Orton and Balfour's 
view of the subject, 112, 1 T3 ; Periodicity as exhibited 
in the phenomena of life, 115-118 ; Historical analysis 
of lunar influence, 12 t ; Dr. Mead's views of the in- 
fluence of the moon upon the bodily health stated at 
length, 120-136; Dr. Pitcairne's case of lunar in- 
fluence, 136; Mr. Cockburn's singular case, 137; 
Hemorrhage from the finger said to come on at the 
fall of the moon, 138 ; Baglioi's singular case, 139 ; 
Remarkable case of lunar influence occurring to Mr. 



xii Contents. 



Ainsworth, 139 ; Van Helmont on the influence of the 
moon on asthma, 139 ; Historical analysis of Dr. 
Balfour's treatise on the influence of the moon, 141- 
146 ; Mr. Francis Day's observations on the influence 
of the moon at Madras, 147 ; Dr. Orton on the effect 
of the moon on the diseases of tropical climates, and 
on the weather, 152-154; Dr. Kennedy's views on 
the same subject, 154 ; Diemerbroeck on the influence 
of the moon on the plague, 155 ; Dr. Lardner's 
opinion of the influence of the moon on the epidemic 
fever of Italy in 1693, 158 ; Dr. James Johnson on 
the effect of the moon on the diseases of the liver, 
159 ; Dr. Scott on planetary influence in modifying 
diseases of tropical climates, 160 ; Mr. Hutton on the 
effects of the moon at Prince of Wales's Island, 161, 
162 ; Dr. Moseley on the effect of the varied phases 
of the moon on hemorrhages of the lungs, 162-164 ; 
Remarkable case illustrative of the fact, 165 ; Nicholas 
Fontana on the influence of the moon on the fever that 
occurred at Barrackpore in 1777, 166 ; Dr. Millingen 
on planetary influence, 168 ; Opinions of the Druids of 
Gaul on the influence of the moon in vegetable produc- 
tions, 170; The mistletoe gathered with a golden 
knife when the moon was six days old, 170; The 
verbena of the ancients supposed to be under plane- 
tary influence, 171 ; Its medicinal and sacerdotal 
virtues, 171; Effect of different phases of the moon on 
the fructification of plants, 172; Instructions for 
planting seeds according to the position of the moon, 
173 ; The Lunar rays calorific, 177 ; Effect of moon- 



Contents. xiii 



light on the thermometer, 177, 178 ; Sudden death and 
coma caused by the moon's light, 179 ; Effect of full 
moon in causing diseases ,of the brain, 179 ; A stroke 
of the moon, 180; Opinion of the Arabs as to the 
morbid influence of the moon, 181 ; On the modus 
operandi of the lunar light, 181 ; Distance of the earth 
from the sun, 182 ; Velocity of planetary light as com- 
pared with that of sound, 183; Humboldt's remarks 
on lunar distances, 185 ; Comparisons of the light of 
sun and moon, 185 ; Michel and Euler on the same 
subject, 186; Arago's observations on the polariscope, 
187; Uses of the polariscope, 188, 189; Sir David 
Brewster on polarized light, 181-192; State of the 
barometer at different phases of the moon, 193-195; 
The influence of the moon on the weather, 198. 



PART III. 

ON THE ALLEGED INFLUENCE OF THE 
MOON ON THE INSANE. 

" Lucid intervals," origin of the term, 199 ; Legal definition 
of the word "lunatic," 199; Meaning of the phrase "lucid 
interval," 200, 201 ; M. D'Aguesseau's analysis of the 
term, 202, 203 ; Dramatic and poetic references to the 
influence of the moon on the mind and passions, 204- 
207 ; The phenomenon of periodicity viewed in relation 
to insanity, 208 ; Illustrations on the subject from the 
writings of Pinel, 208-210; Periodical attacks of 



xiv Contents, 



drunken madness, or dipsomania, 210, 211 ; The 
periodicity explained independently of lunar influence, 
212, 213; Pinel's explanation of the phenomenon, 
213,214; Bouillon and Sauvage's cases of lunar in- 
fluence, 215; Celsus on the influence of the moon, 
215, 216 ; Dr. Haslam's opinion on the same subject, 
217; Dr. Woodward on the influence of the moon 
on the insane, 2T9-221 , Effects of sol-lunar influence 
on maniacal paroxysms, 222 ; Effect of the eclipse of 
the sun in 1806 on the lunatics in Bethlehem Hospital, 
223, 224 ; Daquin on the influence of the moon on 
the insane, 225-228 ; Guislain's opinion on the same 
subject, 228 ; Effect of meteorological phenomena on 
the insane, 229; Sleeplessness and agitation noticed 
among the insane at the full of the moon, 230 ; Effect 
of light and darkness on the illusions and hallucinations 
of the insane, 231, 232 ; Influence of different colours 
on the brain and mind, 234. 



PART IV. 
HYGIENE OF LIGHT. 

Effect of the absence of light on the blood, heart, brain, 
and muscles, 235-237 ; Sir David Brewster on the 
blessings of light, 237 ; On the construction of build- 
ings with the view to the admission of the maximum 
degree of light, 237, 238 ; On the unhealthily-housed 
populations of New York and Bethnal-green, 238, 239 ; 



Contents. xv 



The effect of the absence of light on the poor living in 
courts, narrow streets, &c, 240 ; Sir David Brewster's 
suggestion for remedying this evil, 240, 241 ; On the 
physical condition of the working classes of Edinburgh, 
24 t, 242 ; Sir David Brewster on the value of light as 
a hygienic agent to the poor, 242-246 ; Scorbutic affec- 
tions caused by the absence of light, 246, 247 ; On the 
exclusion of light from young infants and children, 247 ; 
Rules for the treatment of children with reference to 
their being exposed to the influence of light, 248, 249 ; 
Dr. Andrew Wynter's opinion on the subject, 249, 251 ; 
Humboldt on the robust health of the Mexicans, Peru- 
vians, Indians, &c, caused by their being freely exposed 
to light, 251, 252 ; Dr. Bryson on the unhealthy condi- 
tion of seamen confined in dark holds of ships, &c, 
252 ; Judicious hygienic arrangements made for the 
patients of the hospital of St. John, at Brussels, 255 ; 
Importance of light to persons suffering from disease, 
255, 256 ; Florence Nightingale on the construction of 
public hospitals, 257-259 ; The effect of darkness on 
disease as observed in the hospital at St. Petersburg, 260 ; 
Singular case of the same kind related by Baron 
Dupuytren, 260, 261 ; Dr. Hammond on the impor- 
tance of light to the sick, 262 ; The virulence of 
cholera increased by the absence of light, 262, 263 ; 
Injury caused by glaring light and sudden transition 
from darkness to light, 263, 264 ; On disorders of the 
vision caused by a prolonged exposure to intense light, 
265-272 ; The effect of snow and ice upon the eyes of 
sheep, 272 ; Ditto on the Greek soldiers, as related by 



xvi Contents. 



Xenophon, 273 ; The effect of the glare of brilliantly- 
lighted rooms on the organ of vision, 273 ; Injuries 
resulting to the eyes from artificial light, 274 ; Medical 
instructions for the regulation of the different colours 
of light, 275 ; On the probable effect of the vapour of 
iron found in the sunlight by the spectrum on the 
health of the body, 276-278; On the introduction of 
metallic poisons into the body through the skin, 278. 



Appendix Pages 279-301 



ON 



THE INFLUENCE OF LIGHT. 



PART I.— THE SOLAR BEAM. 



cc God said, Let there be light : and there 
was light."* These were the sublime words 
of the Almighty, when, by an act of 
Sovereign power, He willed into existence 
cc two great lights, the greater light to rule 
the day, the lesser light to rule the night." 

The object of the following essay is to 
consider in a philosophical, and I hope a 
reverential spirit, the physiological and 

* "TIN TV") I")** VP —"Be light ! and light was."— 
Gen i. 3. 



On the Sanatory and 



pathological — the healthful and morbid — 
effects upon the animal and vegetable king- 
dom of that principle which, at the fiat of 
the wise and beneficent Creator, radiated 
in all its original glory from the Heavenly 
luminary, and when seen by Him was em- 
phatically pronounced to be cc good." 

This subject has two aspects : of the life- 
giving and benign effects of light I purpose 
fully to speak. It is also my intention to 
consider the baneful influences of the solar 
beam and lunar ray, upon the vegetable 
creation, vital force, physical and mental 
development. 

When speaking of the unalloyed hap- 
piness in store for man in a purer, higher, 
nobler, and beatified state of existence, an 
inspired prophet places prominently in ad- 
vance among the great blessings that will 



Physiological Influence of Light. 3 

be associated with our exemption from the 
pernicious operation of those physical agents 
which in this world are known (under cer- 
tain conditions) to be obnoxious to our well- 
being, the promise, that cc the sun shall not 
smite thee by day nor the moon by night."* 

After so solemn a declaration, need I 
hesitate in approaching the consideration of 
not only the sanatory but the morbid in- 
fluence of the sun upon the human race ; 
and need 1 offer any apology for analyti- 
cally investigating the ^normal as well as 
the normal effects of lunar light on the 
flora of creation, the material and mental 
organization of man ? 

As it would be irrelevant for me to enter 
into the discussion of the varied theories of 
light that have been propounded, I proceed 

* Psalm cxxi. 6. 
B 2 



On the Sanatory and 



at once in the first place to establish non- 
essential the solar beam is to the preserva- 
tion of the bodily and mental health, pro- 
motion of longevity, beauty of the physical 
form, serenity and integrity of the mind.* 

There can be no persistent vitality nor 
healthfully developed bodily structure with- 
out light. If it were possible for a human 
being to be placed during the natural term 
of his existence, in a position of perfect 

* From the earliest periods in the history of Medicine, 
solar heat was considered to prolong human life. u Old 
men," says Hippocrates, a are double their age in winter, 
and younger in summer." In order to obtain the full 
advantages of the light and heat of the sun, the ancients 
had terraces built on the tops of their houses called 
solaria, where they took what was termed their " solar- 
air-bath." Speaking of his uncle, Pliny observes, "Post 
cibum csstate si quid otii,jacebat in sole" As the sun rose, 
disease, according to the views of the ancients, declined. 
" Le<vato sole levatur morbus," was a recognised medical 
axiom in former times. 



Physiological Influence of Light, 5 

darkness, the physical tissues and mental 
faculties would undergo serious modifica- 
tions and degenerations. 

Where light is not permitted to per- 
meate, there are found, in the highest state 
of manifestation, bodily deformities, intel- 
lectual deterioration, crime, disease, early 
and often sudden death. A material, as 
well as a moral and mental, etiolation or 
blanching occurs when the vital stimulus of 
light is withdrawn. 

A vast body of evidence conclusively es- 
tablishes the inestimable value of this agent 
to the health of both body and mind. 
Compare the bright, ruddy, happy faces 
and buoyant spirits of those who reside in 
the country and work in the open fields, and 
upon whom the sun is generally shining, 
with the pale phlegmatic faces, emaciated, 



On the Sanatory and 



stunted forms and nervous depression of 
those whose vocation in life deprives them 
of the health-giving and beneficial influence 
of light. In order properly to test the 
question, place side by side the robust, 
sunny, rosy-cheeked and happy lass or lad 
of the village with the pallid, sickly, melan- 
choly girl or boy residing in one of our 
manufacturing towns, who are pursuing 
their vocation in a room or hermetically 
sealed building, where darkness has obtained 
an undue supremacy. Notice the difference 
between the two classes of human beings ! 
It may be enunciated as an indisputable 
fact, that all who live and pursue their 
calling in situations where the minimum 
degree of light is permitted to penetrate, 
suffer seriously in bodily and mental health. 
These pathological phenomena are prin- 



Physiological Influence of Light. 7 

cipally observed among those confined in 
dark mines and collieries, badly-constructed 
houses containing but few windows, holds 
of ships, factories, and in persons incar- 
cerated in dungeons and buried for a con- 
siderable length of time in prisons, as well 
as the denizens of narrow streets, crowded 
alleys, confined courts, garrets, or cellars, 
where the blessed light of the sun has a 
difficulty in penetrating.* 

The total exclusion of the sun's beams 

* " I never shall forget," says Dr. Hammond, " the ap- 
pearance presented by the sick of a regiment I inspected 
about a year since in Western Virginia. They were 
crowded into a small room, from which the light was 
shut out by blinds of india-rubber cloth. Pale and ex- 
sanguined ghost-like looking forms, they seemed to be 
scarcely mortal. Convalescence was almost impossible; 
and doubtless many of them died, who, had they been 
subjected to the operation of the simplest laws of nature, 
would have recovered."—" Treatise on Hygiene," Phila- 
delphia, 1863, p. 209. 



8 On the Sanatory and 

from the body induces the severer types of 
chlorosis (green sickness) and other anaemic 
conditions depending upon an impoverished 
and disordered state of the blood. Under 
these circumstances, the face assumes a 
death-like paleness, the membranes of 
the eyes become bloodless, and the skin 
shrunken and turned into a white greasy 
waxy colour. 

Associated with these symptoms there are 
emaciation, muscular debility and degenera- 
tion, cedematous conditions, dropsical effu- 
sion, softening of the bones ( <c mollities 
ossium"), general nervous excitability, mor- 
bid irritability of the heart, loss of appetite, 
tendency to syncope and haemorrhages, 
consumption, physical deformity, stunted 
growth, mental impairment and imbecility, 
coupled with premature old age. The off- 



Physiological Influence of Light. 9 

spring of those so unhappily trained are 
often deformed, weak, and puny, and are 
disposed to scrofulous affections. 

The wretchedly unhealthy condition of 
that portion of the working population of 
this country who live and work in darkness 
was satisfactorily proved at the Parliamentary 
inquiry which took place on this subject 
many years ago.* 

Similar consequences are observed in all 
those who labour by night and sleep by 
day ; such as bakers, police-constables, 
compositors connected with the daily press, 
whose occupation necessitates their employ- 
ment during the greater part of the night. 

* The light in the pent-up dwellings of large towns, 
inhabited by the poor, is polarized light, it being always 
only a reflected solar beam. The effect of the light and 
atmosphere contained in such dwellings on the mind as 
well as the body is as previously stated. 



io On the Sanatory and 

The data collected by foreign writers 
fully substantiate this truth. I refer par- 
ticularly to the investigations made and 
facts recorded in reference to the health of 
the miners of Belgium, Hungary, and 
France, as published by Drs. Ozanam, 
Hoffinger, Halle, and M. Dupectiaux.* 
According to the observations of these dis- 
tinguished authorities, the morbid changes 



* I extract the following from the Geelong Advertiser. 
It must be taken quantum valeat. — " It is a curious fact, 
connected with deep mining, that from the hours of 
twelve at night till three in the morning the disturbing 
influence in the bowels of the earth obtains increased 
activity. At that time it is observed by miners that 
water falls from places where none is observable during 
the day. The volume in the wheel is perceptibly in- 
creased, the atmosphere is charged with gases which often 
prevent the lights from burning, and small particles of 
earth and rock are observed to fall from the tops of the 
drives. Whether this phenomenon is to be attributed 
to the diurnal motion of the earth or other causes, it is 
worthy of the attention of the curious." 



Physiological Influence of Light. 1 1 

on body and mind which are consequent 
upon the exclusion of light are singularly 
significant and remarkable. 

In numerous instances the general health 
becomes vitiated, and the function of nu- 
trition seriously interfered with. Not only 
are specific diseases generated, but physical 
as well as mental development arrested. In 
many young girls and boys who are at an 
early age consigned to a life of darkness in 
mines, or in other places, puberty is either 
never attained or is greatly retarded ; in 
fact, the mind as well as body becomes 
impaired in its growth, as the effect of 
light being excluded from the human 
organism. 

No doubt the damaged health of those 
who are constantly working in dark mines 
and collieries is not altogether attributable 
to want of light, although observing and 



12 On the Sanatory and 

practical men have assigned this as one of 
the principal reasons for the physical and 
mental ailments to which this section of the 
labouring classes is liable. 

Fourcault affirms that where life is pro- 
longed perhaps to the average term, the 
evil effects of the want of light are seen in 
the stunted forms and general deteriora- 
tion of the human race. It appears that 
the inhabitants of the arrondissement of 
Chimay, in Belgium, three thousand in 
number, are engaged partly as coal-miners 
and partly as field-labourers. The latter are 
robust, and readily supply their proper num- 
ber of recruits to the army ; while among the 
miners it is in most years impossible to find 
a man who is not ineligible from bodily de- 
formity or arrest of physical development.* 

* Causes Generates des Maladies Chroniques. Paris, 
1844. 



Physiological Influence of Light. 13 

In association with the want of light 
should be considered the deleterious effects 
of dampness, deficient nourishment, impure 
air, over work, anxiety of mind, the inhala- 
tion of noxious and poisonous gases, fine 
dust, &c, upon the general and specific 
health of those exposed to the injurious 
operation of these physical agents. 

With these prefatory remarks I open the 
subject of light in its physiological and 
morbid relations. I would, however, pre- 
mise that it is not my object to discuss the 
special astronomical phenomena of the solar 
ray ; neither do I propose to weigh the 
relative value of the corpuscula, undulatory, 
or other theories of light. I desire to 
restrict my remarks to the direct influence 
of this agent on vital manifestations, and to 
refer to some of the more remarkable facts 



3 4 On the Sanatory and 

illustrative of the effects of the exclusion of 
light on the bodily and mental health, and 
on animal and vegetable life. 

In the first place, I have to point out the 
influence of light on the vital and physical 
organization of different animals. Dr. 
Edwards instituted a number of interesting 
experiments with the view of ascertaining 
the effect of light, independently of heat, 
upon the structure and growth of animals, 
particularly between the interval of concep- 
tion, fecundation, and adult age.* 

This physiologist placed some frog's 
spawn in water. The vessel containing it 
was made impervious to light by being 
covered with dark paper. A similar 
experiment was tried in another vessel 

* "On the Influence of Physical Agents on Life." By 
W. F. Edwards, M.D., F.R.S., 1832. 



Physiological Influence of Light. i^ 

which was transparent. The two vessels 
were exposed to the same degree of 
temperature, but the transparent one was 
placed under the influence of the sun's 
rays. The eggs were developed in succes- 
sion ; of those in the dark none did well. 
Unequivocal indications were observed of 
the transformation of the embryo in a few 
of the eggs. Dr. Edwards' experiments 
were confined to the batrachian family. 
The absence of light did not necessarily 
interfere with the development of these 
reptiles. Two tadpoles, out of twelve con- 
fined in a tin box, pierced with small holes 
for the change of water, and placed at the 
depth of several feet in the Seine, under- 
went the regular change of organic form.* 

*"I have/' says Dr. Hammond, " often repeated Dr. 
Edwards' experiments, and always with analogous results. 



1 6 On the Sanatory and 

It appears that the transformation of two 
of the animals was retarded by the absence 
of light. For the purpose of fully settling 
this question, tadpoles were confined in two 
large vessels, each containing ten litres of 
water, both capable of admitting light ; one 
of glass, but with a partition close to the 
water, to prevent atmospheric respiration ; 
the other open, in order to allow the 
animals an opportunity of rising to the 
surface, and inflating the lungs. Those who 
were deprived of fresh air were later in 
transforming themselves than the others, 
but this delay was so short that the inter- 
ference with the respiration appeared to be 



On one occasion I prevented for 125 days the develop- 
ment of a tadpole, by confining it in a vessel to which 
the rays of light had no access. On placing it in a recep- 
tacle open to light, the transformation was at once com- 
menced, and was effected in fifteen days." 



Physiological Influence of Light. 1 7 

too slight to produce any effect on vital 
development. It was clear that the exclu- 
sion of the light had a serious influence on 
the transformation of the tadpoles plunged 
in water. 

Sir Humphrey Davy refers in one of his 
most charming works to the arrest of de- 
velopment that takes place in the Proteus 
Anguinus consequent upon its exclusion 
from light.* 

In the grotto of the Madalena, he says, 
at Adelsburg, in Illyria, many hundred feet 
below the surface, are seen creatures like 
slender fish, moving in the mud below the 
water. These are the protei : the animal 
is of a fleshy whiteness, and transparent in 
its natural state, but when exposed to light 

* " Salmonia ; or Consolations in Travel." 
C 



On the Sanatory and 



its skin gradually becomes of a darker 
colour, arid at last gains an olive tint. 
Being abundantly furnished with teeth, it 
is inferred that the animal is one of prey, 
yet in its confined state it has never been 
known to eat, and it has been kept alive for 
many years by occasionally changing the 
water in which it was placed. They have 
also been found at a place thirty miles dis- 
tant from the cavern, thrown up by water 
from some subterraneous cavity. In dry 
seasons the protei are very seldom seen in 
the lake of the Madalena, but after great 
rains they are often abundant. Their 
natural residence is an extensive subter- 
raneous lake, from which in great floods 
they are sometimes forced through the 
crevices of the rocks into the place where 
they are found. 



Physiological Influence of Light. \ 9 

These singular creatures Sir H. Davy 
affirms have no organs of vision, but in 
their place are two small dots which occupy 
the position of eyes. It has not been ascer- 
tained that they have any power of percep- 
tion. The entire absence of colour, and 
the imperfect development of their organs, 
in at least their intermediate condition, 
between those of a reptile and a fish, seem 
to be the result of the absence of light. 

Their exclusion from the solar beam is 
well known to produce organic alterations 
in the visual organs of animals, such as 
atrophy of the optic nerve, or those por- 
tions of the brain (the corpora quadri- 
gemina) more immediately associated with 
the sight. It is supposed that the blindness 
observed among fish found in the dark 
caves of the Tyrol and Kentucky arises from 
c % 



20 On the Sanatory and 

the arrest in the development of the eyes as 
the result of a constant deprivation of light. 
In elaborating this subject I have to con- 
sider the effect of solar light and heat in 
discolouring the skin of different races of 
men by producing minute injections of the 
capillary vessels on the surface of the body 
and developing what physiologists term the 
black figment cells. These peculiarities, 
however, are not confined to shades of 
colour, degrees of physical development, 
stature, and power, but extend to the 
animal passions as well as mental energy. 
<c Is not," asks Mr. Hunt, cc the short-lived 
beauty of the oriental women to be attri- 
buted to the influence of that sun 
a Shining on, shining on, by no shadow made tender," 

which is known to give all the grandeur to 
the vegetable world of the east ?" 



Physiological Influence of Light. i\ 

Black, brown, and copper- coloured skins 
are observed among those who reside in 
tropical climates in proportion to the inten- 
sity of the solar light, and the degree to 
which the body is exposed to its influence. 

This discolouration of the skin is not, 
however, perceived among those who live 
in temperate and cold regions. 

As we approach nearer to the pole the 
skin assumes a browner cast. 

This is evidenced among the Laplanders, 
Esquimaux, and Greenlanders. In the arctic 
regions there cannot be said to exist, in the 
right acceptation of the term, any night. 
Here a constant light prevails, if not from 
the sun yet reflected from the snow and ice 
or emitted by the aurora borealis. According 
to Captain Ross the natives of these climes 
suffer from the effects of intense light, and 



22 On the Sanatory and 

are subject to inflammation of the eyes and 
blindness caused by cataract and paralysis of 
the optic nerve. These diseases are not 
confined to the natives. 

Even among the African negroes the 
skin is observed to lose its intense black 
colour, particularly in those whose occupa- 
tion enables them to live for many months 
of the year in the shades of the forest where 
the sun's rays, owing to the thickness of 
the foliage and the size of the trees are 
unable to penetrate. 

It is said that the black colour of the 
negro race is less permanent in its character 
than the red or olive tints. The children 
of olive and copper-coloured parents, ac- 
cording to the authority of Dr. Mason 
Good, exhibit the parental hue from the 
moment of birth, but in those of blacks it 



Physiological Influence of Light. 23 

is occasionally six, eight, or ten months 
before the dark pigment is fully secreted. 
It frequently happens that the black pig- 
ment cells are not matured even among 
negroes. Hence are observed in this 
race of men children with white skins or 
bodies interspersed with only interrupted 
lines of black patches. These are called 
cc spotted negroes." The black pigment has 
been known during attacks of severe illness 
to be entirely absorbed, and a white pigment 
cell developed in its place, thus affording 
a remarkable illustration of a black person 
being suddenly bleached into a white man ! In 
the cc Transactions of the Royal Society" is 
an account of a woman whose left shoulder, 
arm, and hand were as black as an African 
negro's, whilst all the rest of the skin was 
perfectly white. This anomalous condition 



24 On the Sanatory and 

was said to have arisen from her mother 
having during pregnancy put her foot upon 
a lobster ! 

No doubt the coarseness of the wool 
of animals, and hair of human beings, as 
well as the amount of colour developed in 
their skin, is, to a degree, caused by 
the nature of their food. Oils and 
spirits are well known to disorder the liver, 
and those who indulge to excess in these 
articles of diet have generally an excess of 
bile circulating in the blood. Intemperate 
persons addicted to vinous potations have 
a sallow and olive-hued complexion. The 
dark and dingy colour of the pigmy people, 
who live in high northern latitudes, arises 
principally from the fish and oils of a rancid 
and often offensive character upon which 
they mainly subsist. This kind of diet is 



Physiological Influence of Light. 25 

believed not only to affect the colour of the 
skin, but to cause a diminution in the 
stature of this race, in consequence of 
their food being difficult of assimilation 
and defective in nutrition. 

Dr. Mason Good affirms that swine or 
other animals fed on madder root, or 
gallium-verum ( cc yellow-ladies'-bedstraw "), 
have the bones tinged of a deep red or 
yellow colour. M. Huber, the celebrated 
naturalist of Lausanne, was able, by the 
quality of the food given, to convert what 
is commonly, but improperly, called a 
neuter into a queen bee. 

Trinocq, when speaking of the effects of 
light on the colour of the body, affirms, 
that among the Red Indians the skin that 
is not exposed to the influence of the sun's 
rays is quite white ; in other words, the 



26 On the Sanatory and 

face, neck, and hands are dark, whilst the 
limbs which are covered by clothing are of 
an entirely different hue* 

The same phenomena are observed in all 
tropical climates. The white colour of 
animals inhabiting the polar regions is attri- 
butable to the absence of intense sunlight. 

The changes referred to are clearly trace- 
able to the direct influence of the sun, and 
are not exclusively caused by a high degree 
of temperature. Persons who live in hot 
and tropical climates and whose occupation 
exposes them to great heat apart from the 
solar beam coming into immediate contact 
with the body, do not suffer from any 
marked discolouration of the skin.* 



* Gardeners who are occupied for the greater part of 
the day in hot-houses, exposed to intense heat, are not 
generally tanned 



Physiological Influence of Light. 27 

Among the negroes of the torrid zone, 
Albinos are seen ; but these become scarce 
near the equator. It is a commonly ob- 
served fact that among fish, those parts of 
the body not exposed to the free action 
of light become of a pale hue, and are 
sometimes quite white. This fact is no- 
ticed among a certain species of flat-fish. 
The axolotus pisciforniis, syren lacertina, 
and the triton sit tat us (fish that live at 
great sea depths, and are consequently ex- 
cluded from the light), have transparent 
bodies. 

Certain animals, whose natural hue is 
white, if bred and brought up in darkness, 
become completely altered in texture and 
colour. The cockroach, in its normal state, 
is intensely black. If this insect be taken at 
an early stage of its existence and carefully 



28 On the Sanatory and 

reared in darkness, instead of assuming an 
inky hue when it arrives at full growth, 
it becomes nearly white. 

The larvae of most insects that burrow 
in the cavities of the earth, of plants, or of 
animals, are white from the same cause. 
When confined under glasses that admit the 
influence of solar light, they exchange their 
whiteness for a brownish hue. It is said 
that Asiatic and African women confined to 
the walls of their seraglios and secluded 
from the sun are as white as Europeans. 

It is of deep philosophical interest to 
consider in relation to the present subject, 
not only the effect of climate, meteorolo- 
gical changes, combined with the influence 
of varied degrees of light upon the 
general health, great nervous centres, 
and muscular development, but the modi- 



Physiological Influence of Light. 29 

fixations which the physical force under- 
goes from the same causes as far as the 
growth, stature, and longevity of the inhabi- 
tants of various countries are concerned. 

Investigations have been made for the 
purpose of ascertaining the effect of various 
kinds of climate upon the stature of dif- 
ferent nations. It has been satisfactorily 
established that persons placed under the 
same solar influences have not the same 
stature; and, reciprocally the same stature is 
found among people placed relatively to the 
same influence under very different condi- 
tions. The subjoined facts in illustration 
of this subject are quoted from M. Sanson- 
Alphonse's thesis on the influence of light 
and the development of health. 

In the southern hemisphere the Papoes 
of Vaigion, at i° from the Equator, the 



30 On the Sanatory and 

Vankoros at 12 , the Bushmen mountaineers 
at 30 (an Ethiopic race), who receive 
the rays of the sun with great intensity 
of light and heat, have a stature of 
5 ft. 1 in., very little above that of people 
who dwell in the northern hemisphere, the 
Kamschatdales, the Tartars and the Esqui- 
maux (a Mongol race), in latitude 6o° to 70 
north, where only the oblique rays of the 
sun reach them, people of whom the stature 
is 4 ft. 3 in. to 4 ft. 7 in. 

High stature is met with equally in very 
different latitudes ; thus in the southern 
hemisphere we find 5 ft. 10 in. to be the mean 
height of the Caribs (an American race), 
who inhabit regions situate between i° and 
8°, the natives of the " lies Marquises " 
at io°, the inhabitants of the Navigator's 
Islands at 14 . People whose countries 



Physiological Influence of Light. 31 

are very near each other differ considerably 
in stature. Thus the Patagonians, of 
whom the mean height is 5 ft. 10 in., are 
only separated by the narrow straits of 
Magellan from the inhabitants of Terra 
del Fuego, of whom the stature is only 
4 ft. 3 in. ; thus the people of Sweden 
and Finland join the Laplanders ; and the 
New Hebrides, so near the Navigator's 
Islands, whose population have a very high 
stature, are inhabited by a short and badly 
made race. 

People of the same stature dwell either 
in maritime regions on the continents up to 
a level sufficiently elevated above the sea. 
Temperature has certainly more influence 
upon stature than light. 

The inhabitants of very cold regions, 
whether situated near the poles or on the 



32 On the Sanatory and 

tops of mountains covered with snow, are 
small. 

Increase of stoutness is observed among 
people who inhabit regions far from the 
equator, and especially those in which there 
is much moisture. It is there especially that 
the marks of a lymphatic temperament are 
apparent. Under the same zones, but on 
more elevated plains, are seen men who 
combine the greatest bodily development 
with the maximum of muscular power. 
They are of a sanguine temperament. 

In ascending further above the level of 
the sea and up to the regions of snow, the 
men are small, but thick set. 

As we approach the equator and elevated 
regions the inhabitants are withered, with the 
muscular system very moderately developed, 
but endowed relatively with considerable 



Physiological Influence of Light. 33 

energy. Such are especially the Arabs. 
Their constitutions present the character of 
a nervo-bilious temperament. 

Although the free life of savages may 
be favourable to the regular development 
of their forms, they do not acquire under 
the influence of climate any remarkable 
muscular power. 

The natives of Timor, New Holland, 
and Tasmania are very inferior to the 
English sailors in trials of strength 
(Peron). 

The natives of America show the same 
inferiority of physical force. The negro 
race, who bear in the highest degree the 
impress of the effects of light, always ap- 
pear, although individually not the most 
active, the best suited for continued labour 
under the light and heat of the sun. 

D 



34 On the Sanatory and 

Within the limits of climate inhabited by 
the negro race they appear to enjoy a very 
strong constitution. The same observation 
applies to the Arabs. 

The inhabitants of high latitudes consume 
much more food than those who dwell in 
intertropical regions, and have more corpo- 
real development. The superior muscular 
force with which they are endowed is partly 
explained by this great consumption of 
food, by their habits of labour, and the 
consequent increase in the volume of their 
muscles. 

Growth is more rapid in equatorial re- 
gions, and puberty is reached earlier ; but 
the age for marriage ceases sooner. There 
are more examples of longevity among 
the people of the north than among those 
of the torrid zone and more southern 



Physiological Influence of Light. 35 

countries ; but some particular facts would 
lead me to believe that these people would 
also attain a very advanced age.* 

It is not my intention to consider the 
ethnological view of this subject. That 
the influence of solar heat materially modi- 
fies the national character cannot for ,a 
moment be doubted. Like plants and 
animals man, the highest order of intelli- 
gence obeys the laws regulating the world's 
zonal arrangements. According to climate, 
degrees of temperature, &c, the human 
race becomes passive, savage, doltish, or 
intelligent. These affect his physiognomy, 
dialect, and habits of life as well as his 
mode of subsistence. When speaking of 

* "De l'influence de la Lumiere sur le developpe- 
ment et la Sante." Par M. Sanson-Alphonse. (Agrege 
de la Faculte de Medecine de Paris). Paris, 1852. 
D 2 



36 On the Sanatory and 

influences of climate as well as local positions 
upon the physical and mental organization, 
a recent writer observes, after glancing at 
man's geographical position, — cc Here,active, 
intelligent, and progressive ; there, slug- 
gish, dull, and stationary : here, enjoying 
the highest amenities of civilization ; there, 
grovelling in a condition little elevated 
above the brutes by which they are sur- 
rounded. And not merely do they differ 
in intellectual qualities, but in physical 
organization, in mien and stature, in form 
of head and expression of face, in colour of 
skin, in strength and endurance, and, in 
fine, in all those purely bodily qualities by 
which one species of animal is distinguished 
from another."* 

* iC Advanced State of Physical Geography," by D. 
Page. London, 1864. 



Physiological Influence of Light. 37 

I have now to refer to the influence of 
deep sea- water on vegetable and animal life 
( cc flora" and cc fauna"), so far as its stratum 
illustrates the effect of the exclusion of light 
(under these circumstances) in modifying 
vital force, and in interfering with or arrest- 
ing physical development. 

It will, however, be necessary to consider 
preliminarily in connexion with this subject 
two important and interesting questions : 
1 st. What, according to well-ascertained 
data, is the depth of the sea in various 
portions of the globe? 2nd. To what 
extent solar light is known to penetrate the 
ocean ? 

j st. It has been found, owing to the 
irregularity in the form of its basin and a 
variety of other causes, impossible to ascer- 
tain with any degree of scientific exactness 



38 On the Sanatory and 

the. mean depth of the ocean. In consequence 
of the character of the tidal waves and cer- 
tain undulatory movements which occur in 
deep waters, four miles has been said by 
some eminent physicists to be the maximum 
extent to which the plummet has descended.* 



* 6i The mean elevation of all the land-continents, and 
islands, mountains, and plains has been estimated by Hum- 
boldt at somewhat less than 1000 feet ; and the mean 
depth of the ocean has been calculated by Laplace, from 
tidal waves and kindred phenomena, to be at least 21,000 
feet, or about four English miles. We know, however, 
that a very large proportion of the ocean is comparatively 
shallow, and not a tithe of this depth ; and therefore, to 
make up the mean, some other portions must be propor- 
tionally deeper, and to the extent it may be of eight or 
ten miles. Indeed, soundings (no doubt open to question) 
have been made in the South Atlantic, both by British and 
American navigators, varying from 27,000 to 46,000 feet ; 
and soundings, perfectly reliable, have been taken in the 
North Atlantic, off the bank of Newfoundland, to the 
depth of 25,000 feet ; while from calculations on the velo- 
city of tidal waves, which are found to proceed according 



Physiological Influence of Light. 39 

Reliable authorities, however, affirm that 
oceanic soundings have been taken at the 
depth of five, eight, and even to the extent 
of ten miles. There are numerous instances 
where twenty, thirty, forty, or even fifty 
thousand feet of line have been played out 
without giving distinct evidence of its 
having reached the bottom of the sea. I 
state this on the authority of Sir J. 
Herschel. The average depth of the 
Pacific (in consequence of its being abun- 
dantly bestrewn with islands), is said to be 
less than that of the Atlantic Ocean. 

In 1 7 26' S. latitude and 170 29' W. 
longitude, Sir James Rosse found the depth 



to the depth of the channel, it has been estimated that the 
extreme depths of the same ocean are about 50,000 feet, 
or more than nine miles." — (Advanced Text Book of 
Physical Geography, by David Page, F.R.S.E.) 



40 On the Sanatory and 

of the sea to be 14,450 feet. About 450 
miles west of the Cape of Good Hope, it 
was 16,062 feet, or 323 feet more than the 
height of Mont Blanc ; and 900 miles from 
St. Helena, a line of 27,000 feet did not 
reach the bottom of the sea, a depth equal 
to the height of some of the most elevated 
peaks of the Himalaya. It is, however, sup- 
posed that there are many parts of the ocean 
still deeper. Speaking in general terms, the 
depth of the Atlantic averages from three 
to four miles. The cc Telegraphic Plateau," 
stretching from Cape Clear to Cape Race, a 
distance of 1640 miles, is only about 11, coo 
or 12,000 feet in depth ; the greater 
depths (from 4 to 6 miles) have been 
determined in the Indian and Southern 
Oceans. The Arctic is of moderate depth, 
and characterized by great irregularity and 



Physiological Influence, of Light. 41 

diversity. The greatest ascertained depth 
in the Mediterranean is about 13,000 feet; 
in the Red Sea, 6300 feet ; Baltic, 840 
feet ; Caribbean Sea, 14,000 feet ; and in 
the Gulf of Mexico, about 8000 feet. 

2nd. The depth at which solar light is 
believed to permeate the ocean is calculated 
to be about 700 feet.* The distance to 
which the eye can penetrate the sea depends 
principally upon its transparency.! 

In experimentalizing as to the depth of 
the ocean, it has been suggested that inde- 

* In connexion with this subject it is important to 
notice the fact referred to by Sir J. Herschel, viz., that the 
light which penetrates to a great depth in the sea, is very- 
different in its photo-chemical qualities from the solar 
light of the surface. Again, in calculating the degree to 
which the solar beam is seen to pierce the sea it will be 
necessary to bear in mind the effect of various media 
through which light passes on the refraction of its rays. 

f David Page. 



42 On the Sanatory and 

pendently of considering the transparency 
of the water, we should test its phosphor- 
escence, the face of the sky, whether clear or 
cloudy ; the state of the sea, whether rough 
or smooth ; the condition of the weather, 
whether calm or windy. 

The heat of the water should also be tried, 
at various depths and hours of night and 
day, in order to ascertain not only the maxi- 
mum temperature and average depth of the 
warmest stratum in the day, but the differ- 
ence in its temperature and position by day 
and by night.* These observations will 

* Accurate calculations have been made as to the tem- 
perature of the ocean. The results obtained clearly establish 
that the lowest degrees of temperature are obtainable on 
the surface of the water. About ten feet below the sur- 
face the thermometer rises several degrees. Ninety degrees 
is said by Mr. Agassiz (son of Professor Agassiz) to be 
the highest temperature he has known the ocean to 



Physiological Influence of Light. 43 

afford the data, also, for computing the 
amount of solar heat that penetrates the 
bosom of the sea, as well as the amount 
that is radiated thence again. They will 
reveal to us knowledge concerning its acti- 
nometry in other aspects. We shall learn 
how absorption by, as well as radiation 
from, the under strata is affected by a 
rough sea, as when the waves are leaping 
and tossing their white caps ; and how by 
its glassy surface, as when the winds are 
hushed and the sea smooth. 

Mrs. Somerville asserts, that in some 
parts of the Arctic Sea, shells are dis- 
tinctly seen as low down as 80 fathoms ; 
and among the West Indian Islands, at the 
same depth of water the bed of the sea is as 

attain. At very great depths of the ocean a uniform tem- 
perature of about 392- degrees has been found. (D. Page.) 



44 On the Sanatory and 

clear as if seen in air. At this great depth 
shells, corals, and seaweeds of every hue 
display to the eye of the observer the beau- 
tiful prismatic tints of the rainbow. 

In connexion with this subject it is or 
interest to consider the varied colour of the 
sea in different parts of the globe, for upon 
this principally depends the depth at which 
the sight can reach. Assuming as a well- 
established fact that the waters of the ocean 
derive their colour from animalcules of the 
infusorial kind vegetable substances and 
minute particles of matter, it may be affirmed 
as facts recorded by all writers on Physical 
Geography, that the sea is white in the 
Gulf of Guinea, black around the Maldives, 
vermilion off California (caused by the red 
colour of the infusoria it contains), and 
green in the Persian Gulf. 



Physiological Influence of Light. 45 

In the Arctic Sea the colour of the water 
undergoes rapid transitions from ultrama- 
rine to olive green ; from purity to opacity. 
The green colour is said to be produced by 
myriads of minute insects which devour one 
another and are a prey to the whale. The 
varied tints of the ocean in its shallow parts 
depend to a degree upon the sea bed over 
which it passes. A bottom of chalk or 
white sand, produces an apple green colour ; 
over yellow sand, a dark green ; brown or 
black over dark ground ; and grey over 
brown mud.* 

Physicists have instituted a series of in- 
teresting experiments with a view of ascer- 
taining by carefully executed deep sea 
soundings, the maximum depth at which 

* Physical Geography. 



46 On the Sanatory and 

various species of animals (marine molusca 
and those belonging to the inter vertebrate 
class), as well as plants, are capable of 
sustaining life. 

With this object Professor Forbes was 
engaged for a period of eighteen months in 
the iEgean Sea, and on the coast of Asia 
Minor, in sea bottom explorations by means 
of the dredge. He has demonstrated by 
actual observation that below the depth of 
55 fathoms, the number of animals di- 
minishes as we descend, until at the depth 
of about 200 fathoms the number of tes- 
tacea was found to be only eight, and a 
zero in the distribution of animal life was 
indicated at probably about 300 fathoms. 
Green fuci was not found below 55 fathoms, 
and millepoza not deeper than L05 fathoms. 
Similar phenomena are observed in some 



Physiological Influence of Light. 47 

portions of the British Channel, viz., the 
south coast of Cornwall.* 

Professor Bailey of West Point, an emi- 
nent American geographer, naturalist, and 



* The following is the classification of marine animals 
according to the zones of depth at which they live : — 

1 st. Littoral found between high and low water marks, 
a species capable of living in air as well as water, such as 
crustaceous animals, crabs, testacea shell-less animals which 
close themselves up or seal themselves hermetically on the 
rocks and remain dormant during the recess of the water. 
Among these are found the petallas mytilli and littorinas 
purpuras, and among the zoophytes the common sea 
anemone. 

2nd. The circumlittoral zone existing at 15 fathoms. 

3rd. The median zone from 15 to 50 fathoms. 

4th. The infra-median ; and 

5th, the abyssal zone ; the former from 50 to 100 fathoms, 
the latter from thence to the lowest depths at which life is 
possible. 

Sir John Herschel says, when referring to this subject, 
each of these zones is characterized by species which 
belong to no other, and each passes into the other by the 
intermixture of species common to several. 



48 On the Sanatory and 

microscopist, says in a letter to a brother phi- 
losopher, cc the bottom of the ocean at the 
depth of more than 2 miles I hardly hoped 
ever to have a chance of examining ; but, 
thanks to Brooke's contrivance, we have it 
(the deep sea deposit) clean and free from 
grease, so that it can at once be put under 
the microscope. I was delighted to find 
that all these deep soundings are filled with 
microscopic shells ; not a particle of sand or 
gravel exists in them. They are chiefly 
made up of perfect little calcareous shells 
( fC foraminifera "), and contain also a num- 
ber of silicious shells ( cc diatomacece"). It 
is not probable that these animals lived at 
the depths where these shells are found, but 
I rather think that they inhabit the waters 
near the surface, and when they die their 
shells settle at the bottom." Lieut. Brooke, 



Physiological Influence of Light. 49 

of the North Pacific Exploring Expedition, 
procured specimens in the coral sea from 
the bottom at the depth of 2150 fathoms. 
These soundings yielded representatives of 
most of the great groups of microscopic 
organisms. Professor Ehrenberg, of Berlin, 
found the deep sea specimens to consist 
principally of calcareous carapaces, filled 
with soft pulp or fleshy matter. In Dr. 
Wallach's cc Notes on the Presence of 
Animal life in the vast depths of the 
Sea," reference is made to the experiments 
of Capt. Sir Leopold McClintock during 
his survey in H.M. steamer the Bull- 
dog, of the telegraphic route via Green- 
land. It is said this navigator brought up 
from the bottom of the ocean living star 
fish adhering to the deep sea line. Is this, 
it is asked, conclusive proof of the existence 

E 



50 On the Sanatory and 

of animal life in the depths of the ocean ? It 
is supposed that these living star fish took 
hold of the line near the surface of the 
water, and were not actually brought up 
from the bottom of the sea. 

The preceding facts conclusively establish 
the intimate relation existing between each 
solar beam, life and organization as far as 
the sea is concerned. Speaking in general 
terms, it may be affirmed that animal and 
vegetable vitality is incompatible with an 
altitude of a few thousand feet above the sea 
level on land, and a few thousand feet be- 
neath it in the waters. Such is the line of 
demarcation between organic and inorganic 
matter, life and sterility ! 

In connexion with this subject it is essen- 
tial to consider the amount of pressure 
which exists at great oceanic depths, for 



Physiological Influence of Light. 5 1 

upon this often depends the existence of 
marine life. In the Arctic Sea the specific 
gravity of the water is lessened on account 
of the greater proportion of fresh fluid pro- 
duced by the melting of the ice, the pres- 
sure at the depth of a mile and a quarter 
being 2809 pounds on a square inch of sur- 
face. Capt. Scoresby confirms this fact. 
He says in his fC Arctic Voyages" that the 
wood of a boat suddenly dragged to a great 
depth by a whale, was found, when drawn 
up, so saturated with water forced into its 
pores, that it sank in water like a stone for 
a year afterwards. Even sea water is re- 
duced in bulk from 20 to 19 solid inches at 
the depth of 20 miles. The compression 
that a whale can endure is wonderful. 
Many species of fish are capable of sustain- 
ing great pressure, as well as sudden 
e 2 



52 On the Sanatory and 

changes of pressure. Divers in the pearl- 
fisheries exert great muscular strength, but 
man cannot bear the increased pressure at 
great depths, because his lungs are full of 
air, nor can he endure the diminution of it 
at great altitudes above the earth.* 

cc According to experiments, water at the 
depth of iooo feet is compressed ^-h^th of its 
bulk ; and at this ratio the pressure at the 
depth of one mile would be equivalent to 
1 60 atmospheres, or 23201b. on the square 
inch ; while at the depth of 4000 fathoms, 
or about \\ miles, it would amount to 750 
atmospheres ! It is owing to this enormous 
pressure that closed bottles sunk to great 
depths have their corks always forced in ; 
and that pieces of oakwood carried down to 

* Physical Geography, by Mary Somerville. 



Physiological Influence of Light. 53 

similar depths, have their fibres and pores so 
compressed as to be afterwards incapable of 
floating on the surface."* 

I proceed in the next place to notice the 
direct as well as indirect influence of light 
on the vegetable kingdom, particularly in 
reference to the modifications effected in the 
colouring principle of plants, as a conse- 
quence of their exclusion from its opera- 
tion ; but before doing so, I would briefly 
refer to some interesting facts illustra- 
tive of the tendency exhibited by certain 
plants to follow light, from an apparently 
instinctive consciousness of its being neces- 
sary, if not to their existence, at least for 
their well-being. This phenomenon is 
beautifully shown by the following facts : — 

* Physical Geography, by David Page, F.G.S., p. 121 : 
London, 1864. 



^4 On the Sanatory and 

In the spring a potato was left behind in a 
cellar where some tools had been kept during 
the winter, and which had only a small 
aperture at the upper part of one of its 
sides. The potato, which lay in the oppo- 
site corner, shot out a runner which first 
ran twenty feet along the ground, then 
crept up along the wall, and so through the 
opening by which light was admitted.* 

The Chrysanthemum Peruvianum turns 

continually towards the sun, and is said to 

cover itself with dewy clouds which cool 

and refresh the flower during the most 

„ violent heat of the day. 



* " Natural History," by Jesse. 

Asa general rule all plants bend towards the sun. Mr. 
Hunt, however, found that light transmitted through 
red fluid media had the effect of repelling plants from the 
solar beam. This fact, he says, is not susceptible of expla- 
nation. 



Physiological Influence of Light. 55 

Professor Henslow states that some com- 
posite as cc Hypo char is radicata " and 
cc Apirgia autumnalis " are seen in meadows 
where they abound, inclining their flowers 
towards the quarter of the heavens in which 
the sun is shining, Vaucher says the same phe- 
nomena are observed in the Narcissusses and 
in certain species of Melampyrum. Similar 
phenomena have been observed in other 
plants by Priestley, Sennebier, Theodore de 
Saussure, Dumas, and Boussingault. 

If a leafy shoot of any plant is bent down 
without injury so as to reverse the usual posi- 
tion of the faces of the leaves, the latter will 
twist upon their petioles and turn their upper 
surfaces to the light. Shoots of slender- 
stemmed, quick-growing plants, such as jas- 
mine, ampelopsis, &c, when trained into a 
dark recess, turn their growing point back- 



$6 On the Sanatory and 



wards on the older part of the stem, also 
twisting round to face the light. The in- 
fluence of lateral light is distinctly seen in 
the plants grown in rooms in front of the 
windows, while the drawn-up condition of 
closely packed trees is an equally evident 
result of preponderating top light, * 

The curious phenomena previously re- 
ferred to regarding the alteration in the 
colour of plants caused by the absence of 
the solar beam are well known to all intel- 
ligent gardeners and scientific horticulturists. 
Plants, as well as animals, nurtured and 
grown in perfect darkness, never acquire 
their natural colour. The former become 
white instead of green. f 

* "Botany, Structural and Physiological." — By Arthur 
Henfrey, F.R.S., 1857. 
" Audi alteram partem" The following facts appear in 



Physiological Influence of Light. 57 

This fact is observed in the etiolation or 
blanching, as it is termed, of certain kinds 
of vegetables, such as celery, seakale, endive, 
&c. Their leaves deprived of the sun's 

a slight degree to contradict the general law just enuncia- 
ted. u The absence of light exercises a very great influ- 
ence over the power possessed by food in increasing the 
size of animals. Whatever arouses and excites the atten- 
tion of the animal, and makes it restless, increases the 
natural waste of the different parts of the system, and 
diminishes the tendency of food to enlarge the body. 
To the rearers of poultry the rapidity with which 
fowls fatten when kept in the dark is well known ; and 
direct experiment on other animals, whether by keeping 
them in the dark or by the cruel practice of sowing up 
their eyelids, as is adopted in India, have led to similar 
results. Absence of light, from whatever cause produced, 
seems to exercise a soothing and quieting influence on all 
animals, increasing their disposition to take rest, making 
less food necessary, and causing them to store up a greater 
portion of what they eat, in the form of fat and muscle." 
— From a Paper on the " Scientific Principles involved in 
the Feeding and Fattening of Stock," read by Ed. W. 
Davey, M.B.M.R.I., at the Roy. Dub. Soc, April 14, 
1859. 



5 8 On the Sanatory and 

rays do not attain their normal growth or 
form, neither is the natural odour of such 
plants fully developed. Professor Robinson, 
descending into a coal mine, accidentally met 
with a plant growing luxuriantly. Its form 
and qualities were new to him. The sod on 
which it grew was removed, potted and care- 
fully attended to in his garden.* The etio- 
lated plant languished and died ; but the roots 
speedily threw out vigorous shoots which, 
from the form of the leaves and their peculiar 
odour, he readily recognised as tansey. He 
repeated similar experiments upon other 
plants, viz., lovage, carvi, and mint, with 
analogous results. 

Ihe data obtained from the study of 
physical geography conclusively establish 
that animal and vegetable substances near 

* " Encyclopaedia Britannica." 



Physiological Influence of Light, 59 

the surface of the sea are, in consequence of 
their free exposure to light, brilliantly 
coloured, and that they gradually lose the 
brightness of their hues as they descend 
into deep sea water, until the animals of the 
lowest zone are found nearly colourless. 
cc Here," says Mr. Hunt, cc an everlasting 
darkness prevails in the region of silence 
and eternal death." 

The rich colour of seaweed found near 
and on the surface of the water is owing to 
its free exposure to light. The same may be 
said of the lovely tints of some of the zoo- 
phytes {actina) living in shallow waters, 
particularly the sea anemone, which, under 
the influence of the bright sun, is seen, 
whilst adhering to the rocks, to expand 
itself like the blossoms of a flower. 

On the surface of the globe the influence 



60 On the Sanatory and 

of solar rays is shown in a marked manner. 
The animals and plants of tropical climates 
grow with a richness of colour, far exceed- 
ing in beauty and brilliancy those of tem- 
perate zones. The latter are less exuberant 
in their growth, and are of a darker hue. 
In the Arctic regions they are found nearly 
colourless. The changes in vital develop- 
ment which are observed as we approximate 
towards the pole are believed to be governed 
more by the isothermes than by the parallels 
of latitude ; in other words by the mean 
amount of heat diffused.* " Though vege- 



* " The strength of evidence appears to be in favour of 
considering Light, Heat, and Actinism as three distinct 
principles or powers, active in regulating the great pheno- 
mena of Nature. In the sunbeam these powers are 
balanced against each other, and thus are determined those 
differences of climate which are not influenced by the phy- 
sical conformation of the earth's surface."— Hunt. 



Physiological Influence of Light. 61 

tation may greatly differ," says Dr. Draper, 
cc in its luxuriance in different climates of 
the globe, the manner of action of the light 
is always the same. Nothing is gained 

It has been proved by well-conducted observations, that 
with variations of latitude there are variations in the rela- 
tions of these three principles. 

In the temperate regions of the earth the Actinic power 
is active; as we advance to the Tropics, where Heat 
increases, and, 

" The sun shines for ever unchangeably bright ;" 
the chemical power is weak. The photographic picture 
which could be taken in London in a second or two, could 
not be obtained within the Tropics in less then a quarter 
of an hour. It often happens, indeed, that prolonged 
exposure under a blazing sun is insufficient to produce 
any chemical change. Everything appears to favour the 
view that the distribution of plants and animals on the 
surface of the earth is regulated by the balance of physical 
forces in the sunbeam. 

In the Seasons we detect the same influences at work, 
Actinism or chemical power is greatest in the Spring ; as 
the bright Light of Summer advances, the power of the 
Solar rays to produce any chemical change is diminished ; 



62 On the Sanatory and 

under the brilliancy of the tropical skies 
beyond a shortening of the time required 
for the accomplishment of a given amount 
of work. No substances are there decom- 
posed, even in the organism of plants, 
which could not equally well be decomposed 
by the feebler light of more temperate 
climates, only in these it would demand 
more time. The oils and other substances, 
almost or quite free from oxygen, which 
abound in the plants of the torrid zone, are 
not exceptions to, but illustrations of, the 
doctrine here set forth."* 

What is the modus operandi of solar light 



and as we advance to Autumn, the peculiar Heat-rays 
come more evidently into action." — Mr. Hunt, in the 
" Popular Science Review," July, 1862. 

* "Human Physiology, Statical and Dynamical." — 
J. W. Draper, M.D., [858, p. 462. 



Physiological Influence of Light. 63 

in altering if not altogether destroying the 
chlorophyll, or, to use Dr. Hope's term, the 
chromogen or colouring principle of plants ? 
Do these changes depend, as Sir John Her- 
schel suggests, on a cc chromatic analysis by 
which the two distinct elements of colour 
are separated by destroying the one and 
leaving the other outstanding" ? 

Chlorophyll is a substance similar to 
wax in its nature, and is contained in the 
deep cells or mesophyllum of leaves. It 
depends upon the action of light for its 
elaboration, and is intimately associated with 
the phenomena of active vegetable life, has 
a granular form, and is soluble in alcohol.* 
As light decreases in the autumn the chloro- 



* u Chromogen " is said to consist of two separate prin- 
ciples, one of which forms a red compound with acids, 
and the other yellow with alkalies. Dr. Hope attributes 



64. On the Sanatory and 

phyll in many cases diminishes. The 
alteration is caused by the plant losing a 
portion of its carbon. Thus may be ex- 
plained the changes that take place in the 
evergreen and deciduous leaves, producing 
what is commonly known by the autumnal 
tints.* 

The late Professor Lindley made many 
interesting experiments with a view of 
illustrating the physiological influence of 
light on the colour of plants, f He esta- 

the green colour produced by the latter to the mixture of 
the yellow matter with the blue infusion. 

* Balfour. 

f Every plant, from the time of its germination till the 
close of its organic activity, requires for its full develop- 
ment a definite quantity of heat. On this subject Schleiden 
has made some inquiries, and has taken as his subject the 
case of barley. He says " in Egypt, on the banks of the 
Nile, barley is sown at the end of November, and harvested 
at the end of February ; the period of vegetation, there- 



Physiological Influence of Light, 65 

blished that the flowers of the hydrangea 
become blue in a soil impregnated with 
carbonate of iron, and that all the brilliant 
spectacle of vegetable colours disappear 
either in consequence of accidents or on the 
approach of death. In connexion with this 
subject it is curious to notice, he remarks, 
that the discoloration of plants is often 

fore, amounts to about 90 days, and the mean temperature 
of this season is 69 48'. In Tuqueres, near to Cumbal, 
under the equator, the time of harvest the middle of No- 
vember, the mean temperature of this vegetating season of 
168 days is 50 12'. At Santa Fe de Bogota they num- 
ber 122 days between seed time and harvest, with a mean 
temperature of 57 24'. If, now, the number of days is 
multiplied by the figures of the mean temperature, we 
obtain 6282 for Egypt, 8433!^ f° r Tuqueres, for Santa 
Fe, 6489m ; therefore, as nearly the same number as the 
uncertainty in the estimate of the days, the accurate mean 
temperature, and the want of knowledge whether or 
not the same kind of barley is cultivated in all the places, 
will allow us to expect. 
The general result as above detailed is thus generalized 



66 On the Sanatory and 



determined by the same agents, as in other 
cases produce colour, and that certain 
organs which have no colour whilst alive 
when dead have a decided tint! If the 
light be too powerful, a discoloration 
takes place in the plant. Cultivators of 
tulips with a knowledge of this fact place 
their flowers under a tent in order to pre- 
serve them from the effect of the direct 
action of the sun, which is known to alter 

by Dr. Draper: " Every cultivated plant requires a cer- 
tain quantity of heat for its development, but it is the same 
thing whether this heat is distributed over a shorter or 
longer space of time, so that certain limits are not ex- 
ceeded ; for where the mean temperature sinks below 
36 24', or where it rises above 71 36', barley will no 
longer ripen. Consequently, to define accurately the con- 
ditions of temperature which a plant requires to maintain 
it in a flourishing condition, we must state within what 
limits its period of vegetation may vary, and what quan- 
tity of heat it requires. This was first observed by Bous- 
singault."— •" Human Physiology." 



Physiological Influence of Light. 67 

their colours. The organic series of plants 
exhibit the same phenomenon. 

Most aquatic plants, like human beings, 
are said to acquire in death a whitish hue. 
Seaweeds of a most brilliant hue or green 
colour become white when they die. The 
same change is observed in the freshwater 
conferveae. 

Although the parts of plants which 
originally are white or black become more 
or less coloured when exposed to the action 
of light, yet organs, once coloured, do not 
in reality lose their hues when kept in 
'darkness ; if they sometimes appear to do 
so it is owing to this, — that if half developed 
leaves are placed in the dark, they grow 
larger, and the green matter which coloured 
them, being diluted by water and spread 
f 1 



68 On the Sanatory and 



over a greater space, appears to be paler 
without being itself less coloured.* 

When speaking of the influence of the 
sun's light on plants, Dr. Draper says: 
cc Through this agent the decomposition of 
carbonic acid is effected, and the plant 
obtains from the air the carbon it requires, 
out of which its solid structures are for the 
most part built. The rapidity with which 
the reduction of the carbonic acid takes place 
depends upon the brilliancy of the light, 
and the amount of carbon thus obtained 
upon that condition and the time of ex- 
posure conjointly. The amount of light 
received from the sun in any locality depends 
in a general way, as does the heat, upon the 



* On Botany, by Dr. Lindley. 



Physiological Influence of Light. 69 

latitudes, but in both cases a multitude of 
disturbing agencies intervene. Variations 
of moisture control the supply of light by- 
permitting a translucency, or establishing 
its opposite, a cloudiness or murkiness of 
the air. Other meteorological causes, as, 
for example, winds, by condensing or re- 
moving moisture, act in like manner ; so 
also do astronomical conditions, especially 
by influencing the relative length of the day 
and night ; for, as we advance towards the 
pole, the summer sun is above the horizon 
longer and longer. In Northern Europe, 
during the month of June, the sun never 
sets, but remains all night, if night it can be 
called, above the horizon ; and, as Berzelius 
well remarks, cc Under the influence of this 
midnight sun of the North, the life of plants 
runs through the same cycle of change in 



70 On the Sanatory and 

six weeks which it takes four or five months 
to accomplish in beautiful Italy." 

In connexion with this subject it is of 
great interest to consider not only the effect 
of the sun on the colour of man, animals, 
and plants, but its influence on the varied 
phases of insect life. Their maximum 
degree of vital manifestation as well as their 
variety, richness of hue, &c, are found in 
countries where the solar beam attains its 
highest point of development. 

The rate of increase of insect life, in pro- 
ceeding from either pole to the equator, is 
said to be very various in different longi- 
tudes. Their numbers are small in both 
the polar regions— more abundant in Tas- 
mania and New South Wales — more so in 
Southern and Western Africa, Columbia, 
and a maximum in Brazil; but North 



Physiological Influence of Light, 71 

America has fewer species than Europe in 
the same latitude ; and Asia is compara- 
tively poor in species, in proportion to its 
great extent. The horrors of insect annoy- 
ance in the swamps of the great rivers of 
tropical America are vividly described by 
Humboldt. 

The air is one dense cloud of poisonous 
insects to the height of twenty feet. In 
Brazil the vivid colours and metallic brilliancy 
of many of the beetles are extraordinary. 

Among the more remarkable varieties of 
insect life deserve special mention, 1st, the 
bees and ants. Of the former each country 
has peculiar species; but it is singular that 
the honey-bee of North America has been 
introduced from Europe. 

The ants, of which the species are almost 
innumerable, are found chiefly in hot and 



72 On the Sanatory and 

dry climates, and are, perhaps, of all in- 
sects, the most remarkable in their habits. 
The termite of tropical Africa builds pyra- 
midal nests ten or twelve feet in height, 
hollowed into chambers of elaborate struc- 
ture. The white ant of India devours 
everything of animal and vegetable origin, 
ascending by covered galleries (for they can- 
not bear the light) to the sap of furniture, 
beams, &c. But perhaps the most singular 
species of all is that of the parasol ants 
of Trinidad in the West Indies, which walk 
in long procession each carrying a cut leaf 
over its head, as a parasol in the sun, and 
these they deposit in holes ten or twelve 
feet deep under ground apparently with no 
other object than to form a comfortable nest 
for a species of white snake, which is invari- 
ably found coiled up among them on digging 



Physiological Influence of Light. 73 

out the deposit.* The scorpion extends in 
Europe to the north coasts of the Medi- 
terranean, but is more abundant in Africa, 
both North and South, where its bite has 
the singular peculiarity, that, although ex- 
cessively painful on the first occasion of its 
infliction, and even dangerous to life, the 
constitution becomes hardened to it, the 
suffering is less on every subsequent occa- 
sion, and at length comes to be little re- 
garded. Brazil produces a scorpion six 
inches in length. The locust, one of the 
most formidable scourges in countries in- 
fested by it, migrates in such masses as to 
darken the air for successive days, and when 
driven into the sea is sometimes thrown up 



* Mrs. Carmichael's <( Domestic Manners, &c. &c, in 
the West Indies," ii. 327. — Mary Somerville's "Physical 
Geography," from whose works these facts are quoted. 



74 On the Sanatory and 

as banks on the shore, poisoning the air by 
their decomposition for many miles in 
length. They are frequent in Syria and 
Barbary, whence they occasionally migrate 
to Italy, and during the summer of 1858 
several species were taken in the coun- 
try, and one or two in London. They 
are even said to cross the Mozambique 
Channel from the African Coast to Mada- 
gascar.* 

This section of my subject would be im- 
perfectly elaborated if I were to omit all 
reference to the marked effect produced by 
the chemical influence of light in modi- 
fying the active principle of certain medi- 
cinal drugs. f The phenomena referred to 

* As quoted by Sir John Herschel : « Physical Geo- 
graphy," 
f Dr. Draper performed some interesting experiments 



Physiological Influence of Light. 75 

are of deep practical importance, not only 
to the pharmaceutical chemist but to the 
physician. If the powdered leaves of hem- 
lock, aconite, foxglove, or henbane, are ex- 
posed for any length of time to a strong 
light, their colour becomes changed, cc pass- 
ing," says Mr. Hunt, Cf slowly from a green 
into a slaty grey, and ultimately into a dirty 
yellow." A decomposition also takes place 
by which the medicinal activity of the plant is 
seriously altered if not made altogether inert. 
Hence the importance of preserving the 
previously mentioned pharmaceutical pre- 



on the production of hydrochloric acid by the direct 
union of chlorine and hydrogen under the influence of 
light, both artificial and solar, and also on the decom- 
position of peroxalate of iron, from which the carbonic 
acid is readily disengaged, by which he established that 
the primary condition essential for the chemical action of 
light is the absorption of some of its rays, 



j 6 On the Sanatory and 

parations in well-covered bottles, thus care- 
fully excluding them from the influence of 
the sun's rays. 

By what chemical or physiological laws 
are we to explain the curious facts referred 
to by Mr. Hunt, when alluding to the 
effect of light in modifying the potency of 
some vegetable tinctures, and particular 
medicinal powders ? Pulverized rhubarb 
and ginger adhere with considerable firmness 
to the sides of the bottles exposed to the 
light, whereas the sides in shadow are left 
clear. If camphor is kept in a bottle, crys- 
tals will be formed on the sides of the glass 
upon which the light falls. If that side is 
turned from the light the crystals will be 
gradually removed, and again be deposited 
on those parts upon which the rays of light 
first impinge. 



Physiological Influence of Light. 77 

Hydrocyanic acid is supposed to undergo 
decomposition if exposed to the action of 
light ; hence it is preserved in blue-coloured 
bottles. 

Gum guaiacum is well known to turn green 
under the prolonged influence of the solar 
light. Dr. Wollaston took two specimens 
of paper coloured with a yellow solution of 
this gum in alcohol, and exposed one of 
them to air and sunshine, the other to air 
in the dark. The former was turned per- 
ceptibly green in five minutes, and the 
change was complete in a few hours, while 
the latter was not discoloured after the lapse 
of many months. 

In connexion with this subject, I have to 
consider in detail the exceedingly interesting 
experiments which have been made with a 
view of ascertaining the modifications that 



78 On the Sanatory and 

take place in the vital and chemical influence 
of light when passed through media of 
varied tints. Apart from the coloured rays 
observed when the spectrum is subjected to 
the effects of some absorbing medium, there 
is an agent which is said to permeate the 
glass or fluid, which has a decided thermic 
influence. These phenomena are recorded 
with philosophic exactness by Mr. Hunt. 
The following is a summary of the facts he 
has conclusively established in relation to 
this subject : the highest degree of tempera- 
ture is not obtained behind red media, but a 
yellow or orange tint ; in fact, the maximum 
degree of temperature is found behind a 
colourless fluid. Red glasses and fluids 
absorb a larger quantity of the heat rays 
than any others excepting black ones. The 
effect of the rays of light passing through 



Physiological Influence of Light. 79 

different coloured media on the germination 
of plants has been beautifully illustrated. 

The following is the order in which the 
colours standi when viewed in relation to 
their vital or germinating effects : 1, orange ; 
2, red ; 3, ruby ; 4, yellow ; 5, blue ; 6, 
green. " The roots of tulips/ says Mr. 
Hunt, fC under the orange glass, developed 
the cotyledons a week earlier than those 
under the yellow, blue, or green glasses. 
The greatest progress in germination was 
made by the tulips under the yellow and 
orange glasses ; but the leaves under each of 
these were by no means healthy, particularly 
under the yellow glass, but which had a 
singular delicate appearance, being of a very 
light green colour, and covered with a most 
delicate white bloom." 

Under the influence of the colour pre- 



80 On the Sanatory and 

viously referred to, the leaf stalks of the 
tulips shot up remarkably long, and were in 
both cases white. Under the orange glass, 
a small flower bud appeared in the plant ; 
it, however, soon perished with the plant 
itself. Under the yellow glass no buds 
appeared, and the vitality of the plant soon 
failed. Tulips exposed to the influence of 
light passing through ruby and red glasses 
shot up in a single lobe. The duration of 
the life of the plant did not extend over 
three or four weeks, and it did not rise over 
two or three inches above the soil. Under- 
neath the green glass the plants grew slowly 
but strongly. The stem was long, having a 
small leaf at the end, not more than two- 
thirds of an inch in diameter. The flower- 
buds generated under these circumstances 
never could be made to blossom, notwith- 



Physiological Influence of Light, 81 

standing the greatest care and attention was 
bestowed upon them. The attempt to 
develop the bud appeared to exhaust the 
vitality of the plant, and it soon died. 
Under blue glasses the roots germinated 
less quickly than in the open ground, but 
exhibited a greater degree of vitality. Some- 
what similar phenomena were observed with 
regard to the germination of seeds when 
exposed to the influence of light passing 
through various coloured media, solid or 
fluid in their nature. Dr. Draper found 
that under the influence of the bright sun 
of Virginia, plants have grown well in the 
light which has been made to permeate 
through a considerable thickness of intense 
yellow solution. 

When considering the chemical and phy- 
siological influence of light it is impossible 



82 On the Sanatory and 

to overlook the important results obtained by 
Professors Bunsen and Kirchhoff by the aid 
of the spectroscope, or analysis of the sun- 
light by the prism. When this instrument 
is applied to the investigation of a solar beam 
it is found to be traversed by a number 
of vertical dark lines, ( cc Fraunhofer's lines," 
as they are designated.)* The* sunlight is 

* " In order to explain the occurrence of the dark lines 
in the solar spectrum, we must assume that the solar 
atmosphere incloses a luminous nucleus, producing a con- 
tinuous spectrum, the brightness of which exceeds a 
certain limit. The most probable supposition which can 
be made respecting the Sun's constitution is, that it con- 
sists of a solid or liquid nucleus, heated to a temperature 
of the brightest whiteness, surrounded by an atmosphere 
of somewhat lower temperature. This supposition is 
in accordance with Laplace's celebrated nebular theory- 
respecting the formation of our planetary system. If 
the matter, now concentrated in the several heavenly 
bodies, existed in former times as an extended and con- 
tinuous mass of vapour, by the contraction of which sun, 
planets, and moons have been formed all these bodies 



Physiological Influence of Light. 83 

thus proved to contain various metals. 
Among these are iron, nickel, sodium, 
calcium, magnesium, chromium, and in small 
quantities, barium, copper, and zinc. Gold, 
silver, mercury, aluminium, cadmium, tin, 
lead, antimony, arsenic, strontium, and 
lithium are not, according to the experiments 
of Professor Kirchhoff, found in the solar 

must necessarily possess mainly the same constitution. 
Geology teaches us that the earth once existed in a state 
of fusion ; and we are compelled to admit that the same 
state of things has occurred in the other members of our 
solar system. The amount of cooling which the various 
heavenly bodies have undergone, in accordance with the 
laws of radiation of heat, differs greatly, owing mainly 
to difference in their masses. Thus whilst the moon has 
become cooler than the earth, the temperature of the 
surface of the sun has not sunk below a white heat. 
Our terrestrial atmosphere, in which now so few elements 
are found, must have possessed, when the earth was' in a 
state of fusion, a much more complicated composition, as 
it then contained all those substances which are volatile at 
a white heat. The solar atmosphere at this present 

G 2 



84 On the Sanatory and 

atmosphere. It is supposed that the rays 
of light which form the solar spectrum and 
present the interesting phenomena previously 
referred to have passed through the vapour 
of iron, and have thus suffered the absorp- 
tion which the vapour of iron must exert. 
It has been maintained that these iron 



time possesses a similar constitution. The idea that the 
sun is an incandescent body is so old, that we find it 
spoken of by the Greek philosophers. When the solar 
spots were first discovered, Galileo described them as 
being clouds floating in the gaseous atmosphere of the 
sun, appearing to us as dark spots on the bright body of 
the luminary. He says that if the earth were a self- 
luminous body, and viewed from a distance, it would 
present the same phenomena as we see in the sun. — 
u Researches on the Solar Spectrum and the Spectra of 
the Chemical Elements." By G. Kirchhoff, Professor of 
Physics in the University of Heidelberg. Translated by 
Henry E. Roscoe, B.A., Professor of Chemistry, Owen's 
College, Manchester. London, 1862. 



Physiological Influence of Light. 85 

vapours are contained in the atmosphere of 
the sun or in that of the earth. cc It is 
not easy to understand," says Professor 
KirchhofF, cc how our atmosphere can con- 
tain such a quantity of iron vapour as would 
produce the very distinct absorption lines 
which are seen in the solar spectrum. This 
supposition is rendered still less probable 
by the fact that these lines do not appreci- 
ably alter when the sun approaches the 
horizon. 

cc It does not, on the other hand, seem at 
all unlikely, owing to the high temperature 
which we must suppose the sun's atmo- 
sphere to possess, that such vapours should 
be present in it. Hence the observations 
of the solar spectrum appear to prove the 
presence of iron vapour in the solar atmo- 
sphere with as great a degree of certainty as 



86 On the Sanatory and 

can be attained in any question of natural 
science.* 

The important results thus obtained re- 
garding the properties of light by means of 
the solar spectrum, will in all probability 
tend greatly to elucidate the physical consti- 
tution of the sun, the nebular theory respect- 
ing the formation of the planetary system, 
and the geological character of the earth ; 
but into the consideration of the various 
hypotheses suggested to explain the pheno- 
mena relating to these interesting philoso- 
phical points, it would be foreign to my 
purpose to enter. 

When addressing myself to the hygienic 
influence of light, I purpose again recurring 
to Professor Bunsen and KirchhofPs dis- 



* " Researches on the Solar Spectrum, &c." By Pro- 
fessor Kirchhoff. 



Physiological Influence of Light. 87 

covery, for the purpose of ascertaining to 
what extent the development of the red- 
blood cell and the iron found in the general 
circulation depend upon the mechanical or 
chemical effect of the solar beam (contain- 
ing in its composition this metal) upon the 
portions of the body exposed to its opera- 
tion. 

It is not my intention to analyse the 
morbid effects of solar light in the gene- 
ration of specific diseases. I leave the 
consideration of this portion of the sub- 
ject in the able hands of Sir James Ranald 
Martin, and other well-known writers on 
the Diseases of Tropical Climates. 

That a prolonged exposure to the intense 
rays of the sun injuriously affects the 
health is generally admitted. Inflammation 
and congestion of the brain ; engorgement, 



88 On the Sanatory and 

inflammation, enlargement, and torpidity 
of the liver ; intermittent, remittent, gas- 
tric, yellow, and congestive fevers ; dysen- 
tery, and cholera, are among the principal 
maladies incidental to a protracted residence 
in the tropical zone. 

Fatal attacks of what in India is termed 
cc heat apoplexy," or cc coup-de-soleil," are 
common in various parts of that country, 
as the effect of an indiscreet exposure to 
the vertical rays of the sun. 



Physiological Influence of Light. 89 



PART II. 



THE LUNAR RAY. 



I would refer briefly to the ancient opinions 
respecting the influence of the moon. 
From the earliest periods of antiquity, 
the idea generally prevailed, not only that 
the moon exercised a specific effect in 
the production and modification of dis- 
ease, mental and bodily, but played a pro- 
minent and important part in the develop- 
ment of the character of nations, and in 
determining the destinies of the human 
race. Amongst the ancients the moon 
was viewed as an object of superstitious 
regard. They held her in great religious 



90 On the Sanatory and 

veneration, considering her influence supe- 
rior even to that of the sun ; in fact, they 
worshipped her as a Deity. The new 
moons, or the first days of the month, were 
kept with great pomp and ceremony as 
national festivals. The people were obliged 
to rest on those days. The feast of new 
moons was a miniature of the feasts of the 
prophets. Eclipses, whether of the sun or 
moon, were looked upon as evidences of 
Divine displeasure. The Greeks consulted 
the different phases of the moon before con- 
tracting marriage, and the full moon, or 
the times of conjunction of sun and moon, 
were considered the most favourable periods 
for celebrating the ceremony, in conse- 
quence of the impression that the reproduc- 
tive functions were under lunar influence. 

" This connexion of the moon," says Dr. 
Laycock, cc with the measure of time seems 



Physiological Influence of Light. 9 1 

to have brought that planet into relation 
with the religious rites of ancient nations, 
as the Egyptians and Jews ; and, also, to 
have given origin (in part) to the mytho- 
logical idea so extensively prevalent of a 
lunar influence on marriage and child-bear- 
ing. Even the barbarous Greenlanders, as 
Egede informs us, believe in this super- 
stitious notion. They absurdly imagine that 
the moon visits their wives now and then ; and 
that staring long at it when at its full will 
make a maid pregnant! Amongst the ancient 
nations the general idea was, that the lunar 
influence varied according to the age of the 
moon. Bubastis, the Egyptian Diana, was 
not equally favourable to parturient females 
and their offspring in her different phases. 
Amongst the Jews the full moon was 
believed to be lucky, and the other phases 
disastrous." 



92 On the Sanatory and 

cc The full moon/' says the Rabbi Abra- 
vanel, cc is propitious to new-born children : 
but if the child be born in the increase or 
wane, the horns of that planet cause death ; 
or, if it survive, it is generally guilty of 
some enormous crime." The Greeks and 
Romans entertained a similar idea respect- 
ing the lunar phases. The general opinion 
seems to have been, that the moon was 
propitious in proportion as its luminous 
face was on the increase. The ancient 
Greeks considered the day of the full 
moon to be the best day for marriage. 
Euripides makes Agamemnon answer, 
when asked on what day he intends to 
be married, 

u Orav "2e\r)vr]s evrvxrjs e'X^?y kvkXos" * 

Hesiod asserted that the fourth day of 

* u Iphigenia," act v. 717. 



Physiological Influence of Light. 93 

the moon was propitious, but the eighteenth 
was bad, especially to females. Aristotle 
maintained that the bodies of animals were 
cold in the decrease of the moon, and that 
the blood and humours are then put in 
motion, and to those revolutions he ascribes 
the various derangements peculiar to women. 

Lucilius, the Roman satirist, says that 
oysters and echini fatten during lunar aug- 
mentation, which also, according to Gellius, 
enlarges the eyes of cats ; and that onions 
throw out their buds in the decrease of the 
moon, and wither in her increase, which 
induced the people of Pelusium to avoid 
their use. Horace also notices the supe- 
riority of shell-fish during the moon's in- 
crease. 

Pliny takes notice of the same fact. He 
also adds that the streaks on the livers of 



94 On the Sanatory and 

rats answer to the days of the moon's age ; 
and that ants never work at the time of the 
lunar changes. He also informs us that 
the fourth day of the moon determines the 
prevalent wind of the month, and con- 
firms the opinion of Aristotle that earth- 
quakes generally occur about the new moon. 
Pliny asserts that the moon corrupts all 
dead carcases exposed to its rays, and pro- 
duces drowsiness and stupor in those who 
sleep under her beams. He further con- 
tends that the moon is nourished by rivers, 
as the sun is fed by the sea. Galen asserted 
that all animals who are born when the 
moon is falciform, or at the half quarter, 
are weak, feeble, and short-lived ; whereas 
those who come into the world during the 
full moon are healthy, vigorous, and long- 
lived. 



Physiological Influence of Light. 95 

Lord Bacon adopted the notion of the 
ancients. He maintained that the moon de- 
veloped heat, induced putrefaction, increased 
moisture, and excited the motion of the 
spirits.* Van Helmont affirmed that a 
wound inflicted during the period of moon- 
light is most difficult to heal, and boldly 
asserted, that if a frog be washed clean and 
tied to a stake under the rays of the moon 
in a cold winter's night, on the following 
morning the body will be found dissolved 
into a gelatinous substance bearing the 
shape of the reptile, and that coldness 
alone, without the lunar action^ will never 
produce the same effect ! 

The Spartans considered the moon to 
have great influence, and no motive could 

* It is recorded that this great philosopher always had 
a severe attack of syncope at the time of a lunar eclipse. 



9 6 On the Sanatory and 

induce them to enter upon an expedition, 
or march against the enemy, until the full 
of the moon. The Greeks and Romans 
believed that the moon presided over child- 
birth. The patricians of Rome wore the 
figure of a crescent upon their shoes, to 
distinguish them from the inferior order of 
men. The crescent was called lulula. Hero- 
dotus records that when the Lacedaemonians 
visited Athens, after the battle of Marathon, 
they waited until the moon had passed its 
full before they continued their march.* 
The ancient alchymists attempted to localize 
planetary influences, maintaining that the 
heart, which represented, according to their 
physiological notions, the vital principle, was 
under the special protection of the sun ; that 

* Erato, lxx. 



Physiological Influence of Light. 97 

the brain was regulated and controlled by the 
moon ; that Jupiter presided over the lungs, 
Mars the liver, Saturn the spleen; that 
Venus took the kidneys under her kind con- 
trol, and Mercury sat in judgment upon the 
reproductive functions. They were also of 
opinion that the morning regulated the 
blood, noon the bile, evening the atra-bile, 
and night the cold phlegmatic constitution. 

It will appear by the previously recorded 
data that from the earliest periods in the 
history of the world the idea of the phe- 
nomena of organic life being subject to 
planetary control, was popular amongst 
enlightened and philosophic men.* The 

* " A knowledge of the ancient and popular belief in 
Sidereal influence will enable us to explain many super- 
stitions in physic ; the custom, for instance, of adminis- 
tering cathartic medicines at stated periods and seasons, 
originated in an impression of their being more active at 



98 On the Sanatory and 

following passage proves that the great 

particular stages of the moon, or at certain conjunctions 
of the planets ; a remnant of this superstition still exists 
to a considerable extent in Germany ; and the practice of 
bleeding at < spring and fall/ so long observed in this 
country, owed its existence to a similar belief. It was in 
consequence of the same superstition that the metals were 
first distinguished by the names and signs of the planets ; 
and as the latter were supposed to hold dominion over 
time, so were astrologers led to believe that some, more 
than others, had an influence on certain days of the week; 
and, moreover, that they could impart to the correspond- 
ing metals considerable efficacy upon the particular days 
which were devoted to them ; from the same belief, some 
bodies were only prepared on certain days in the year ; 
the celebrated earth of Lcmnos was, as Galen describes, 
periodically dug with great ceremony, and it continued 
for many ages to be highly esteemed for its virtues ; even 
at this day, the pit in which the clay is found is annually 
opened with solemn rites by the priests, on the 6th day 
of August, six hours after sunrising, when a quantity is 
taken out, washed, dried, and then sealed with the Grand 
Signior's seal, and sent to Constantinople. Formerly it 
was death to open the pit or to seal the earth on any 
other day in the year. In the botanical history of the 
Middle Ages, as more especially developed in Macer's 



Physiological Influence of Light, 99 

Roman satirist believed in lunar influ- 
ences : — 

u Ut mala quern scabies aut morbus regius urguet, 
Aut fanaticus error, et iracunda Diana, 
Vesanum tetigisse timent fugiuntque poetam, 
Qui sapiunt."* 

These notions have not been confined 
to classical regions, ancient authorities, 
or to the fanciful creations of the poet. 
They have existed amongst barbarous, un- 
civilized, and unlearned nations, who were 
profoundly ignorant of the views pro- 
pounded by the astrologers of old, or by 
the medical writers, who had somewhat en- 
Herbal, there was not a plant of medicinal use that was 
not placed under the dominion of some planet, and must 
neither be gathered nor applied but with observances that 
savoured of the most absurd superstition, and which we 
find were preserved as late as the seventeenth century by 
the astrological herbarists, Turner, Culpepper, and Lovel." 
— Dr. Paris's " Pharmacologia." 

* Hor. " Ars Poetica." 

H 2 



ioo On the Sanatory and 

grafted the study of medicine upon that of 
astrology and astronomy. In referring to 
the alliance which formerly obtained between 
the two sciences, it has been well observed 
by an able writer and close observer of 
nature, cc that no judicious person can doubt 
that the application of astrology to medi- 
cine, though it was soon perverted and 
debased till it became a mere craft, originated 
in actual observations of the connexion be- 
tween certain bodily affections and certain 
times and seasons. Many, if not most, of 
the mischievous systems in physics and 
divinity have arisen from dim perception or 
erroneous apprehensions of some important 
truth, and not a few have originated in the 
common error of drawing bold and hasty 
inferences from weak premises."* 

* Southey. 



Physiological Influence of Light, toi 

That the theory of planetary influence 
should have been advocated in early times, 
and have found zealous supporters, not only 
amongst the illiterate, but amongst learned 
and scholastic men, need not excite surprise 
when we consider how easily susceptible of 
demonstration is the fact of the moon's 
powerful effect in producing that regular 
flux and reflux of the sea which we call 
tides. Astronomers having admitted that 
the moon was capable of producing this 
physical effect upon the waters of the ocean, 
it was not altogether unnatural that the 
notion should become not only a generally 
received, but a popular one, that the ebb 
and flow of the tides had a material influence 
over the bodily functions. The Spaniards 
imagine that all who die of chronic diseases 
breathe their last during the ebb. Southey 



102 On the Sanatory and 

says, that amGngst the wonders of the isles 
and city of Cadiz, which the historian of 
that city Suares de Salazar enumerates, one 
is according to P. Labat, that the sick 
never die there while the tide is rising or at 
its height, but always during the ebb. He 
restricts the notion to the isle of Leon, but 
implies that the effect was there believed to 
take place in diseases of all kinds acute as 
well as chronic. <c Him fever," says the 
Negro in the West Indies, " shall go when 
the water come low ; him always come not 
when the tide high." The popular notion 
amongst the Negroes appears to be that 
the ebb and flow of the tides are caused 
by a "fever of the sea" which rages for six 
hours, and then intermits for as many more. 
There exists in the writings of many 
able, truthful, and conscientious men a 



Physiological Influence of Light. 103 

vast body of valuable and indisputable 
evidence in support of the theory of plane- 
tary influence. I subjoin the names of 
the principal authorities on the subject : — 
Ballonius, Ramazzini,* Joubertus,f Joannes 
Morellus,! Mead, § Gemma, || Paraeus,^[ Dr. 
Nicolas Fontana,** Dr. Cullen,tt Dr. 
Balfour,!! Dr. James Lind,§§ Dr. Jack- 



* De Constitutionibus trium sequentium annorum, 1692, 
1693, 1694, in mutinense civitate et illius Ditione, Dis- 
sertatio ; which essay will be found in the first volume of 
his Opera Omnia Medica et Physiologica. 

f On Epidemics. ! On Putrid Fever. 

§ De Imperio Solis et Lunge in corpora humana et 
Morbis inde oriundis. 

j| On the Plague of 1575. % On the Plague. 

** Osservazioni sopra le Malattie che attacano li Europei 
nei Climi caldi, &c. Livorno, T781. 

ff First Lines. 

XX Effects of Sol-Lunar Influence in Fevers. London, 
1815. §§ On Putrid Fevers. 



104 On the Sanatory and 

son,* Dr. James M c Grigor,t Dr. James Gil- 
christ, t Dr. James Johnson,§ Dr. Liddell,|| 
Dr. Diemerbroeck ;% and in our own imme- 
diate epoch, Drs. Orton,** RadclifFe, and 
Laycock on the periodicity connected with dis- 
ease and associated with the vital phenomenaft 
—Sir James Ranald Martin, C.B., F.R.S.,tt 
Dr. Milligan,§§ William Ramsay, |||| Dr. 



* Treatise on the Connexion of the New and Full 
Moon with the Invasion and Relapse of Fevers. — London 
Medical Journal for 1787. Also, his Treatise on the 
Fever of Jamaica. 

f Medical Sketches of an Expedition to Egypt. 

J On the Diseases of India. 

§ On the Diseases of Tropical Climates. 

|| On the Diseases of Tropical Climates. 

^| On the Plague. 

« On Cholera. 

■j-j- Vols. ii. and iii., Lancet ; 1842-3. 

++ On the Diseases of Tropical Climates, Second 
Edition. 

§ § Curiosities of Medical Experience. 
|| Astrologia Restaurata. 



Physiological Influence of Light. 105 

Prichard,* Arago,t and Dr. Lardner.J 
Many of the great medical authorities of 
antiquity were clearly of opinion that the 
celestial bodies exercised a marked influence 
upon the bodily and mental functions. 
Dr. Haslam asserts that Hippocrates, whom 
he designates as a cc philosopher and correct 
observer of natural phenomena," did not 
place any faith in the generally received 
notion respecting the influence of the moon. 
This is clearly an error. Hippocrates im- 
bibed so strong a belief regarding the effects 
of the celestial bodies upon the vital mani- 
festations that he expressly recommends no 
physician to be entrusted with the treatment 
of disease who was ignorant of astronomical 
science ; and he expressly advises his son 

* Analysis of the Egyptian Mythology, 
f Meteorological Essays. 



io6 On the Sanatory and 

Thessalus, to study the science of numbers 
and geometry, affirming that the "rising 
and setting of the stars have great effect 
upon the distempers."* 

The critical days, or crises as they were 
termed, were said to correspond with the in- 
terval between the moon's principal phases.f 
Galen adopted the Hippocratic notion. 
Hence the lunar periods were said by him 
to be connected with the exacerbation of 
particular diseases. 

The doctrine of lunar influence has de- 
scended to modern times, and notwithstand- 
ing a section of the scientific world has 

* Epist. ad Thessalum de aere, aquis, et locis. 
f The crises which Hippocrates describes by the words 
imperfecte judicabantur, were, according to Dr. Balfour, 
nothing more than intermediate inter-lunar crises; and 
those to which he applies the terms perfecte judicabantur, 
were final inter-lunar crises. 



Physiological Influence of Light. 107 

altogether repudiated the idea, it has never- 
theless found zealous advocates among 
learned men. Writers of admitted judg- 
ment and sagacity have been recognised in 
the ranks of those who support this theory. 
At the threshold of this important and 
interesting inquiry it will be well to pause 
and consider, why any number of men of 
science should exhibit a disposition to dis- 
countenance this notion of planetary in- 
fluence ? Dr. Orton endeavours to answer 
the question. 

cc The difficulty of explaining lunar in- 
fluence appears to be the great obstacle 
which in modern times has stood in the way 
of the belief of its existence and general 
prevalence. The ancients, who less minutely 
scrutinized the chain which connects effects 
with remote causes, implicitly believed in 



io8 On the Sanatory and 

the existence of this power, simply be- 
cause they saw the coincidence of its 
effects and certain states of the heavenly 
bodies, although they knew not that these 
bodies in other respects exert a physical 
influence on the earth. But since the pro- 
gress of science has enabled men to trace 
more distinctly the manner in which changes 
arise from and produce other changes, this 
empirical mode of reasoning has ceased to 
be satisfactory ; and the improvement of 
philosophy seems, in some instances, to have 
actually operated as a barrier to its further 
progress, by furnishing negative arguments 
against the existence of causes which we are 
unable to connect by any satisfactory theory 
with their effects. Every occurrence in 
Nature has been attempted to be accounted 
for on rational and general principles, and 



Physiological Influence of Light. 109 

it has been found much easier to deny than 
to explain the operation of the sol-lunar 
power. If, however, these principles were 
to be applied in all their extent to the other 
branches of medicine, they would strike at 
the very root of that imperfect science ; for 
we know little more of the modus operandi 
by which ipecacuanha produces vomiting, 
or jalap produces purging, than we do of 
that by which the new or full moon pro- 
duces attacks of intermittent fever, of 
mania, or epilepsy. We have the same 
kind of evidence of the agency of both these 
classes of causes ; and after the proofs which 
have been adduced of sol-lunar influence, it 
would be nearly as preposterous to deny its 
existence — because we cannot account for it, 
because it does not produce its effects on all 
persons, or because the same occurrences 



no On the Sanatory and 

frequently arise without its agency, as it 
would be to assert that a common dose of 
ipecacuanha or jalap will not produce vomit- 
ing or purging for precisely the same 
reasons. It does not, nevertheless, appear 
to be impossible to make some approach to 
the explanation of the nature of sol-lunar 
influence on known principles. It is proved, 
on the known laws of gravitation, that the 
various situations of the moon necessarily 
must have determinate effects on the 
atmosphere. Observations have shown 
that such is the case, and on these 
data considerable progress has already been 
made in the elucidation of this interesting 
subject. 

cc It appears to be very evident that 
sol-lunar influence is much more powerful 
within the tropics than in other parts of the 



Physiological Influence of Light. 1 1 1 

world ; and this may in some degree account 
for the little credit which it has met with ; 
for little information, in comparison to the 
opportunities which are presented, has been 
conveyed from these countries to the native 
regions of philosophy. Dr. Balfour has 
indeed been impressed with all the impor- 
tance of his subject, and even more than all ; 
his situation and experience were such as to 
entitle his opinions to the highest attention, 
and he has given them to the world in the 
fullest manner ; but he has failed in gaining 
a complete credit, probably from the dog- 
matical style which he has adopted, and 
from his having fallen into the error which 
is usually fatal to theorists — that of aiming 
at too much."* 

* Dr. Reginald Orton's "Essay on the Epidemic 
Cholera of India," p. 202. 1831. 



ii2 On the Sanatory and 

Dr. Balfour's treatise will form the basis 
of some remarks when I come particularly 
to analyse the facts recorded by the different 
authorities relative to lunar influence in the 
production of disease. There has, I think, 
been a disposition to discourage of late years 
any minute, special, and scientific investiga- 
tion of the facts recorded by men of veracity, 
on the presumption that the subject is alto- 
gether fanciful, visionary, and Utopian. If 
the question has been seriously considered 
with a view to elicit truth, has the inquiry 
been calmly and dispassionately pursued, 
and that, too, by competent observers, 
possessed of the preliminary amount of 
mathematical, astronomical, and meteoro- 
logical science indispensably necessary in 
order to arrive at anything like a satisfactory 
result or scientific conclusion ? I much 



Physiological Influence of Light. 1 13 

doubt the fact. In general conversation on 
the subject^ the observation is often made, 
cc Oh, I have not overlooked the study of 
the subject ; I have been careful to observe 
whether the moon does really exercise any 
influence in modifying the type of disease, 
and have arrived at the conclusion that the 
notion is a puerile and fallacious one." 
But when the question is asked as to the 
mode of investigation which has been adopted, 
it will generally be found to have been loose 
and unscientific. With undoubtedly a 
sincere disposition to arrive at the truth, the 
method adopted by the inquirer has not been 
so sufficiently philosophic, logical, and exact 
as to entitle it to the respect of learned men. 
To establish the inconsistency displayed by 
writers on the subject, Dr. Orton cites 
passages from two standard works of 



r 14 On the Sanatory and 

scientific reference, relating to the subject 
of lunar light, in which the authors deny 
in toto its effects on the human organism. 
"The hypothesis of planetary influence," 
says one of the authorities, cc has originated 
and passed by with the age of astrology."* 
Another writer remarks that, Cf as the 
most accurate and sensible barometer is not 
affected by the various positions of the 
moon, it is not thought likely that the 
human body should be affected by them." 
cc But in the following page," says Dr. 
Orton, cc the writer furnishes a body of 
evidence to establish that the barometer has 
been found to be very remarkably affected by 
the various positions of the moon" It is not 
easy to reconcile such statements. 

* Rees' a Encyclopaedia." " Encyclopaedia Britannica." 



Physiological Influence of Light. 115 

Before proceeding to analyse the facts 
cited by the authorities previously referred 
to, as illustrative of the influence of lunar 
light in the production of bodily disease, I 
would briefly direct attention to some of 
the well-known data regarding periodicity , as 
associated with the origin, progress, and type 
of disease. The theory of lunar influence 
is in a great measure based upon this well- 
established law. The doctrine of periodi- 
city, as exhibited in the phenomena of life, 
is not altogether of modern origin.* The 
ancients were too close and accurate stu- 
dents and observers of nature to have 

* Certain plants appear, in an inexplicable manner, to 
be influenced by the law of periodicity as well as by light. 
Dr. Balfour, when referring to this subject, observes that a 
plant accustomed to flower in daylight at a certain time 
will continue to expand its flowers at the wonted time, 
even when kept in a dark room. De Candolle made a 

I % 



n6 On the Sanatory and 

overlooked the fact. The phenomena of 
menstruation were the subject of particular 
observation in all ages, and its singular and 
well-marked periodical character was attri- 
buted to the operation of causes acting 
independently of those organic laws sup- 
posed to regulate the special functions of 
life. This periodicity is observed in a large 
class of febrile affections, particularly in the 
intermittent, remittent, and bilious fevers 
of tropical climates, in the class of disease 
termed neuroses, in all spasmodic and con- 
vulsive disorders, particularly in epilepsy 
and its allied affections, in many forms of 

series of experiments on the flowering of plants kept in 
darkness and in a cellar lighted by lamps. He found that 
the law of periodicity continued to operate for a consider- 
able time, and that in artificial light some flowers opened, 
while others, such as species of convolvulus, still followed 
the clock hours in their opening and closing. 



Physiological Influence of Light. 117 

insanity, and in the diseases classed under 
the term exanthemata. 

There is much in the recorded facts and 
observations embodied in the valuable trea- 
tises of Drs. Mead and Balfour, to strengthen 
the presumption that the periodicity re- 
ferred to arises directly or indirectly from sol- 
lunar influences. Medical meteorology has 
not yet assumed the character and position 
of an exact and demonstrative science, and 
although I would concede much to those 
who have patiently considered this interest- 
ing branch of philosophic inquiry, I am in 
duty bound to pause before attributing too 
much power to those external agents (active 
I admit them to be) that are considered to 
regulate and control the great principle of 
life, either in its healthy or morbid mani- 
festations. Can it not be demonstrated that 



it 8 On the Sanatory and 

the vital law regulating the phenomena of 
menstruation acts independently of certain 
external agencies ? I repeat, is this fact not 
susceptible of proof? Until we are satisfied 
that this important uterine function is not 
dependent upon a special organic law in- 
herent in or acting specifically upon the 
uterus itself, shall we not be travelling 
beyond the limits of a safe and logical 
induction, by assuming as an indisputable 
and demonstrable fact, that the phenomena 
to which I refer are the effect of lunar 
conditions, or dependent upon certain 
meteorological states of the atmosphere in- 
duced by the physical aspects of the moon ?* 



* These periodical discharges are said to be more pro- 
fuse in countries near the equator than towards the poles. 
Hippocrates notices this fact, and uses it to explain the 
sterility of the women of Scythia. 



Physiological Influence of Light. 119 

I now proceed with the historical analysis 
of the subject. 

Dr. Mead's treatise* appeared soon after 
Sir Isaac Newton's immortal discoveries 
burst like a flood of dazzling light upon the 
world. Dr. Mead occupied a high position 
amongst the literati of Europe. His repu- 
tation as a scholar, physician, man of 
letters, and a lover and cultivator of science, 
was universally established. He was the 
intimate friend of Pope, Newton, and of 
Halley. He stood high in the estimation 
of foreign princes and kings, and the learned 
and scientific men of all countries eagerly 
sought his acquaintance, and felt honoured 
by his friendship. It is recorded in his 
biography that the King of Naples for- 

a De Imperio Solis et Lunae in corpora humana et 
Moibis inde oriundis." 



120 On the Sanatory and 

warded to Dr. Mead the two first volumes 
of Signor Bajardi's erudite work on the 
antiquities of Herculaneum, paying him the 
compliment of asking in return a complete 
collection of his own works, and at the 
same time inviting him to his palace, for 
the purpose of showing him his valuable 
collection of Herculaneum antiquities. Con- 
sidering the position of Dr. Mead, every- 
thing that fell from his pen was read with 
avidity, and his observations on all subjects 
were considered to be based upon a patient 
and accurate study of the great book of 
nature. His work, previously referred to, 
was read with universal interest ; and al- 
though it gave rise to much controversy, it 
nevertheless commanded the respect of his 
learned contemporaries. It was the first 
modern treatise on the subject, and proceed- 



Physiological Influence of Light, 121 

ing from a physician of Mead's reputation, 
it at once formed the topic of general con- 
versation and criticism. Such being the 
character of the work, I proceed briefly to 
analyse its contents. 

Dr. Mead, in the prefatory part of his 
treatise, dwells much upon the importance 
of a previous acquaintance with the mathe- 
matical principles of natural philosophy, in 
order fully to comprehend the subject of 
lunar influences. 

He then attempts to demonstrate, in the 
first place, that the sun and moon, in pro- 
portion as they approach near the earth, 
independently of their influence upon heat 
and moisture, must, at certain times, mate- 
rially modify vital phenomena. The author, 
in the second place, cites facts illustra- 
tive of his theory, and then makes some 



122 On the Sanatory and 

suggestions in reference to the practical 
division of the subject. 

Dr. Mead enters fully into the considera- 
tion of the effect of the moon on the winds, 
observing that the most boisterous seasons 
of the year occur about the vernal and 
autumnal equinox. It is a matter, he re- 
marks, of common observation, that in the 
calmest weather there is some breeze at 
mid- day, at mid-night, and also at full sea 
— that is, about the time the sun and moon 
arrive at the meridian, either over or under 
our hemisphere. Without entering more 
minutely into analysis of Dr. Mead's able 
and ingenious essay, his theory of sol-lunar 
influence may be thus briefly epitomized : 
— According to Dr. Mead, the attraction of 
the sun and moon being increased at the 
syzygies (new and full moon), and the 



Physiological Influence of Light. 123 

perigees (those situations in the moon's 
orbit in which she approaches nearest to the 
earth), and the passages over the equator, 
the weight of the atmosphere is consequently 
diminished, and it is rendered mechanically 
unfit for respiration, and for supporting the 
due degree of pressure on the surface of the 
body. Dr. Mead endeavours to establish, 
on Newtonian principles that in all the 
situations in which the sun and moon have 
been found to produce their greatest effects 
in raising the tides, rarefying and disturbing 
the atmosphere, and in producing disease, 
their joint attraction for the earth, or 
certain parts of it is greatest ; and, on the 
contrary where these effects are least evi- 
dent, that these attractions are least. Dr. 
Mead maintains that the atmosphere is much 
more under lunar attraction than the ocean, 



•124 On the Sanatory and 

owing to its greater height, which removes 
it further from the earth and nearer to the 
moon. Dr. Mead supposes that the influ- 
ence of the moon is most visible in low 
conditions of vitality and in certain states of 
disease, and its effects are said to be more 
manifest on the nerve force than on the blood, 
or any other of the animal fluids. I consider 
it, however, fair that Dr. Mead should, to 
a certain extent, be the exponent of his own 
views. I therefore make no apology for 
quoting, in extenso, two important passages 
from his treatise, having special reference 
to his theory of lunar influence : — 

cc It has been for a considerable time 
established that our atmosphere is a thin 
elastic fluid, one part of which gravitates 
upon another, and whose pressure is com- 
municated every way in a sphere to any 



Physiological Influence of Light. 1 25 

given part thereof. From hence it follows 
that if by any external cause the gravity 
of any one part should be diminished, the 
more heavy air would rush in from all sides 
around this part to restore the equilibrium 
which must of necessity be preserved in 
all fluids. Now this violent running in 
of the heavier air would certainly pro- 
duce a wind, which is no more than a 
strong motion of the air in some determined 
direction. If, therefore, we can find any 
general cause that would, at these stated 
seasons which we have mentioned, diminish 
the weight or pressure of the atmosphere, 
we shall have the genuine reason of these 
periodical winds, and the necessary conse- 
quences thereof. The flux and reflux of 
the sea was a phenomenon too visible, too 
regular, and too much conducing to the 



126 On the Sanatory and 

subsistence of mankind, and all other 
animals, to be neglected by those who 
applied themselves to the study of nature. 
However, all their attempts to explain this 
admirable contrivance of infinite wisdom 
were unsuccessful till Sir Isaac Newton 
revealed to the world juster principles, and, 
by a truer philosophy than was formerly 
known, showed us how, by the united or 
divided forces of the sun and moon, which 
are increased and lessened by several circum- 
stances, all the varieties of the tides are 
accounted for. And since all the changes 
we have enumerated in the atmosphere do 
fall out at the same times when those 
happen in the ocean, and likewise whereas 
both the waters of the sea, and the air of 
our earth, are fluids subject in a great mea- 
sure to the same laws of motion, it is plain 



Physiological Influence of Light. 127 

that the rule of our great philosopher takes 
place here— viz., that natural effects of the 
same kind are to be attributed as much as 
possible to the same causes.* What differ- 
ence that known property of the air, which 
is not in water, makes in the case, I shall 
show anon. Setting aside the considera- 
tion of that for the present, it is certain that, 
as the sea is, so must our air, twice every 
twenty-five hours, be raised upwards to a 
considerable height, by the attraction of the 
moon coming to the meridian ; so that, 
instead of a spherical, it must form itself 
into a spheroidal figure, whose longest 
diameter, being produced, would pass 
through the moon. That the like raising 
must follow, as soon as the sun is in the 

* Sir I. Newton's u Principia," p. 387. 



128 On the Sanatory and 

meridian of any place either above or below 
the horizon ; and that the moon's power of 
producing this effect exceeds that of the 
sun in the proportion of four and a half to 
one nearly. Moreover, that this elevation 
is greatest upon the new and full moons, 
because both sun and moon do then conspire 
in their attraction ; least on the quarters, in 
that they then are drawing different ways, 
it is only the difference of their actions that 
produces this effect ; lastly, that this in- 
tumescence will be of a middle degree at 
the time between the quarters and new 
and full moon. The different distances of 
the moon in her perigasum and apogaeum 
likewise increase or diminish this power. 
Besides, the sun's lesser distance from the 
earth in winter is the reason that the greatest 
and least attraction of the air upwards more 



Physiological Influence of Light. 129 

frequently happens a little before the vernal 
and the autumnal equinox. And in places 
where the moon declines from the equator, 
the attraction is greater and lesser alternately, 
on account of the diurnal rotation of the 
earth on its axis. 

cc Whatever has been said on this head is 
no more than applying what Sir Isaac 
Newton has demonstrated of the sea to our 
atmosphere ; and it is needless to show how 
necessarily those appearances just now men- 
tioned of winds, at the stated times, must 
happen hereupon. It will be of more use 
to consider the proportion of the forces of 
the two luminaries upon the air to that 
which they have upon the waters of our 
globe, that it may the more plainly appear 
what influence the alterations hereby made 
must have upon the animal body." 

K 



130 On the Sanatory and 

Dr. Mead then proceeds to demonstrate 
how much more powerfully the moon in- 
fluences the atmosphere than the sea, and 
that the tides in the air, from lunar attrac- 
tion, are much greater than on those of the 
ocean ; and, after considering the effect of 
certain unnatural states of the atmosphere 
upon the barometer, and then the connexion 
between certain states of the barometer and 
special as well as epidemic diseases, he, in 
the subjoined passage, further developes his 
views as to the mechanical influence of cer- 
tain conditions of the atmosphere on the 
respiratory organs : — 

cc It will not be difficult to show that these 
changes in our atmosphere at high water, new 
and full moon, the equinoxes, &c, must oc- 
casion some alterations in all animal bodies, 
and that from the following considerations: — 



Physiological Influence of Light. 131 

cc 1 st. — All living creatures require air 
of a determined gravity, to perform re- 
spiration easily and with advantage, for it 
is by its weight chiefly that this fluid in- 
sinuates itself into the lungs. Now, the 
gravity, as we have proved, being lessened 
by these seasons, a smaller quantity 
than usual will insinuate itself; and this 
must be of smaller force to comminute 
the blood and forward its passage 
into the left ventricle of the heart, 
whence a slower circulation ensues, and 
the secretion of the nervous fluid is di- 
minished. 

<c 2nd. — This effect will be the more sure 
in that the elasticity of the atmosphere 
is likewise diminished. Air proper for re- 
spiration must be, not only heavy, but also 
elastic to a certain degree ; for as this is by 
k 2 



132 On the Sanatory and 

its weight forced into the cavity of the thorax 
in inspiration, so the muscles of the thorax 
and abdomen press it into the most minute 
ramifications of the bronchia in expiration ; 
where, the bending force being somewhat 
taken off, and springy bodies, when un- 
bended, exerting their power every way in 
proportion to their pressures, the parts of 
the air push against all the sides of the 
vesiculae and promote the passage of the 
blood. Therefore, the same things which 
cause any alterations in the property of the 
air will more or less disturb the animal 
motions. We have a convincing instance 
of all this in those who go to the top of 
high mountains ; for the air is there so pure 
(as they call it) — that is, thin — and wants so 
much of its gravity and elasticity, that they 
cannot take in a sufficient quantity of it to 



Physiological Influence of Light. 133 

inflate the lungs, and therefore breathe with 
great difficulty. 

"3rd. — All the fluids in animals have 
in them a mixture of elastic aura, which, 
uhen set at liberty, shows its energy, and 
causes those intestine motions we observe in 
the blood and spirits, the excess of which is 
checked by the external ambient air, while 
these juices are contained in their proper 
vessels. Now, when the pressure of the 
atmosphere upon the surface of our body is 
diminished, the inward air in the vessels 
must necessarily be enabled to exert its 
force in proportion to the lessening of the 
gravity and elasticity of the outward ; here- 
upon the juices begin to ferment, change 
the union and cohesion of their parts, and 
stretch the vessels to such a degree as some- 
times to burst the smallest of them. This 



134 On the Sanatory and 

is very plain in living creatures put into the 
receiver exhausted by the air-pump, which 
always first pant for breath, and then swell, 
as the air is more and more drawn out ; 
their lungs at the same time contracting 
themselves, and falling so together as to be 
hardly discernible, especially in the lesser 
animals."* 

Making due allowance for the obsolete 
terms used by Dr. Mead, as well as for the 
state of pathological and physiological science 
of his epoch, the reader will be able to detect, 
in the language which he adopts to enunciate 
the theory of lunar influence, the germs of 
some great truths, which have subsequently 
been confirmed, in all quarters of the globe, 
by appeals to the great book of nature. 
Dr. Mead has undoubtedly laid himself 

* " Espericnzc dell' Accademia del Cimento," p. 118. 



Physiological Influence of Light* \$$ 

ge of at 
too much ; 

tors of />sed to the 

..-i ? 

of fa< l 

-).-, well u the oba 

,"; ^r 
of the cases cited 

into which the 
author has f 
to substantiate his pet ( 

admit that it is to a great 
tit based on ■■ and accurate obser- 

and inaccu- 

1. It will be interesting, whilst 



13 6 On the Sanatory and 

glancing at the literary history of this sub- 
ject, to refer to some of Dr. Mead's illustra- 
tions. Dr. Mead was physician to St. 
Thomas's Hospital during the time of 
Queen Anne's wars with France, and whilst 
occupying this honourable position, a great 
number of wounded sailors were brought 
into the hospital. He observed that the 
moon's influence was visible on most of the 
men at that time under his care. He then cites 
a case, communicated to him by Dr. Pitcairne, 
of a patient, thirty years of age, who was 
subject to epistaxis, whose affection returned 
every year in March and September — that 
is, at the new moon near the vernal and 
autumnal equinoxes. Dr. Pitcairne's own 
case is referred to as a remarkable fact 
corroborative of lunar influence. In the 
month of February, 1687, whilst at a country 



Physiological Influence of Light. 137 

seat near Edinburgh, he was seized, at nine 
in the morning, the very hour of the new 
moon, with a violent haemorrhage from the 
nose, accompanied with severe syncope. 
On the following day, on his return to 
town, he found that the barometer was 
lower at that very hour than either he or 
his friend Dr. Gregory, who kept the 
journal of the weather, had ever observed 
it ; and that another friend of his, Mr. 
Cockburn, professor of philosophy, had died 
suddenly, at the same hour, from haemor- 
rhage from the lungs, and also that six of his 
patients were seized, at the same time, with 
various kinds of hemorrhages •, all arising, it 
was supposed, from the effect of lunar 
influence on the condition of the barometer. 
He refers to the case of a young man, of 
delicate habit who brought on an attack of 



138 On the Sanatory and 

haemoptysis by making an effort beyond his 
strength. The haemorrhage during eighteen 
months regularly recurred at the full of the 
moon. Two remarkable instances, illus- 
trative of the same fact, are recorded in the 
"Philosophical Transactions."* The first 
is that of a young man who, from his child- 
hood till the twenty-fifth year of his age, dis- 
charged a small quantity of blood from the 
corner of the thumb-nail of his left hand, 
every time the moon came to its full. The 
other is the case of a patient, who from 
the fifty-third to the fifty-fifth year of his 
age, had a periodical evacuation of blood 
from the extremity of the forefinger of 
his right hand. 

Baglivi cites the case of a student at 
Rome who had a fistulous ulcer of the 

* Nos. 171 and 172. 



Physiological Influence of Light. 139 

abdomen which appeared to have some 
connexion with the colon. This discharged 
so abundantly on the increase, and so little 
on the decrease of the moon, that it served 
him as a perfect index of the periods and 
quadratures of that planet. Nephritic 
attacks, he says, frequently follow the 
course of lunar attraction. 

Tulpius relates that Mr. Ainsworth, an 
English clergyman at Amsterdam, constantly 
suffered from an attack of the gravel, ac- 
companied with suppression of flatus, at the 
full of the moon, which continued until she 
had made some progress in waning. Van 
Helmont mentions this influence of the 
moon on asthma; and Sir John Fluyer, who, 
from being personally afflicted with this 
disease, had more occasion to attend to its 
phenomena than most people, asserts that 



140 On the Sanatory and 

paroxysms of asthma are always most 
severe at certain periods of the moon, and 
commonly recur with the change. Still 
more extraordinary effects are attributed to 
the lunar influence. The celebrated Kerck- 
ringius, in his Anatomical Observations, 
mentions the case of a young lady who 
became plump and handsome with the in- 
crease of the moon, but who completely 
changed with the decrease of that planet. 
About the change, she became so disfigured 
and haggard that she secluded herself from 
all society for some days. Mead also refers 
to a lady, whose countenance always de- 
veloped itself with the increase of the moon, 
so that the eclat of her charms always de- 
pended upon that planet. 

Having given the preceding sketch of 
Dr. Mead's essay, I now proceed to analyse 



Physiological Influence of Light. J41 

Dr. Balfour's treatise, the second work of any 
importance specially devoted to this subject. 
Dr. Francis Balfour's first dissertation 
appeared in Calcutta, in 1784.* In 1790, 
in a cc Treatise on Putrid Intestinal Re- 
mitting Fevers," published at Edinburgh, 
the periodical return of febrile paroxysms 
and their coincidence with the periodical re- 
volutions and remissions of sol-lunar power, 
which constitutes the foundation and proof 
of this theory, was investigated, described, 
and illustrated by two different plates, ex- 
hibiting a synoptical view of the whole 
system. The first part of that treatise is a 
regular logical synthesis, arising from facts 
observed and collected by himself to the 

* "Treatise on the Influence of the Moon in Fevers." 
This was subsequently reprinted in England, and in- 
serted in Dr. Duncan's "Medical Commentaries." 



142 On the Sanatory and 

discovery of certain prevailing tendencies in 
nature, and thence to axioms or general 
laws. The second part is an analysis, in 
which these axioms or laws are employed to 
explain some of the most remarkable phe- 
nomena of fevers. The third part is an 
application of the principles of this theory 
to form general rules for practice. 

This physician appears to have devoted 
great attention to the consideration of this 
subtle and disputed point in science, and, 
with a view to its satisfactory elucidation 
placed himself in communication with all 
the medical men of note resident in our 
Indian presidencies, eliciting from them the 
result of their observations on the subject. 
Dr. Balfour maintains, that every type of 
fever prevalent in India is, in a remarkable 



Physiological Influence of Light. 1 43 

manner, affected by the revolutions of the 
moon. Whatever may be the form of 
fever, he says that he has invariably ob- 
served that its first attack is on one of the 
three days which immediately precede or 
follow the full or the change of the moon, so 
that the connexion which prevailed between 
the attack of the disease and the moon at 
or during the time referred to, was most 
remarkable. Relapses in cases of fever are 
also said frequently to occur at such times. 
Dr. Balfour has observed for a period of 
fourteen years, this tendency to relapse at 
the lunar full and change ; and, in particu- 
lar cases, he was able to prognosticate the 
return of the fever at these periods with 
almost as much confidence as he could fore- 
tell the moon's revolution itself. Putrid, 



144 On the Sanatory and 

nervous, and rheumatic fevers of India are, 
according to Balfour, equally under the 
influence of the moon. In attempting to 
explain these phenomena, Dr. Balfour says, 
that along with the full and change of the 
moon there is constantly recurring some un- 
common or adventitious state or quality in 
the air which increases fever and disposes 
to an unfavourable termination or crisis ; 
and that along with the intervals there is 
constantly recurring a state or quality in the 
air opposite to the former, which does not 
excite but diminishes fever and disposes 
to a favourable crisis.* Dr. Balfour has 

* It will be well to state what Dr. Balfour means by a 
crisis. He defines it to be " favourable changes which 
never fail to take place, in some degree or other, at the 
time of their transition from the lunar period in the inter- 
lunar interval, and generally on the first morning inter- 
meridional interval after it j at which juncture the 



Physiological Influence of Light. 1 45 

collected a vast body of valuable evidence 
in support of his lunar theory, establishing 
beyond all dispute that in tropical climates 
the regular diurnal and septenary changes 
observed in the character of the fevers of 
India are coincident and correspondent with 
periodical sol-lunar conditions. 

In the year 1783-4, Dr. Balfour had for 
many months the charge of a regiment of 
sepoys, in Cooch Behar, immediately under 
the vast range of mountains which separate 



maturity of the critical disposition concurs with the 
periodical decline of sol-lunar influence in bringing them 
about; and they are distinguished by one or more of 
the following symptoms — viz., a sediment, or particular 
turbid appearance, of the renal secretion ; a more free and 
natural perspiration ; spontaneous evacuations; and cleaner, 
moister, and softer tongue, with a more free and natural 
discharge of saliva, a more loose and copious expectora* 
tion, and a free discharge of bile, which seems to disappear 
and be suppressed in the course of the fever," &c. 



146 On the Sanatory and 

the northern part of Bengal from Bootan. 
The prevalent diseases were fevers, or 
cc fluxes" attended with fevers. During 
the first month four hundred men were 
invalided. The greater part, however, of 
these cases were convalescent in the course 
of the eight days that intervened between 
the full and change of the moon ; but 
during the remaining months of his stay in 
that district, the diseases previously men- 
tioned increased to almost double their 
extent at every full and change of the moon, 
falling down again to their former standard 
during the eight days which intervened 
between these two periods. With regard 
to small-pox occurring in India, Dr. Bal- 
four expresses himself as perfectly satisfied 
that the full and change of the moon 
interfered with the eruption, and increased 



Physiological Influence of Light. 147 

the accompanying fever to a dangerous 
degree. 

Mr. Francis Day, of the Madras army, 
thus generalizes Dr. Balfour's observations: 

1. That the influence of the moon is less 
apparent in Madras than in Bengal, but 
may be traced over every portion of our 
Eastern possessions. 

2. That the lunar influence is thus 
exerted : — The first attack of fever almost 
invariably commences on one of those days 
preceding the full or new moon, or on one of 
those three which immediately follow them, 
but that the last three are the most violent 
in their effects. 

3. That the new moon is more injurious 
than the full. 

4. That during these times the most 
severe as well as the greatest number of 

l 2 



j 48 On the Sanatory and 

cases take place, but that when they occur 
at other periods they are less severe, and of 
short duration. 

5. That these laws are as applicable to 
relapses as they are to primary attacks ; so 
much so, that the author was often able to 
prognosticate the return of the fever at these 
periods with almost as much certainty as he 
could foretell the revolution (of the moon) 
itself. 

Mr. Day epitomises the results of care- 
fully prepared statistical observations as 
follows: — 

1. That no decided preponderance in the 
admissions for malarious fever is observed 
at the time of the new moon. 

2. That a decided preponderance is ob- 
served at the time of the full moon. 

3. That more admissions occur in the 



Physiological Influence of Light. 149 

three days preceding the full moon than in 
the three days subsequent to those changes. 

4. That a slight increase in the admissions 
may be present about the first and third 
lunar quarters. 

5. That the cases admitted at the time of 
the new moon are generally slightly more 
severe than the average admissions. 

6. That the cases admitted at the time of 
full moon are much more severe than the 
average admissions. 

7. That at times increased severity is 
also apparent at the first and third lunar 
quarters. 

8. That the cases admitted during the 
three days preceding these changes are more 
severe than those admitted in the three 
subsequent ones. 

From the entire series of cases, Mr. Day 



150 On the Sanatory and 

arrives at the probability that there is a 
sol-lunar influence which is greater in the 
equinoctial period than in the respective 
equinoctial intervals, and considerably 
more so in the autumn than in the vernal 
equinoctial period ; that this force is greater 
at the full and new moon than at the 
intervals, and much more so at the full 
than at the new ; that it is greater during 
the meridional period than at the intermeri- 
dional intervals, and much more so at the 
diurno-meridional than at the nocturno- 
meridional periods.* 

The influence of the moon on the func- 
tions of life has been made the subject of 



* Quoted from Sir J. Ranald Martin's valuable work 
on the (i Influence of Tropical Climates in producing 
the Acute Endemic Diseases of Europeans." London, 
1861. 



Physiological Influence of Light. 151 

observation and speculation in every part of 
India. The physiological and pathological 
effects of lunar light have been universally 
acknowledged by all medical men practising 
in tropical climates. The natives of India 
are taught to believe in lunar influence from 
early infancy. In the northern latitudes 
the effects of the moon's rays are said to 
be less sensibly felt than in India. In 
the latter country, those suffering from 
attacks of intermittent fever are often 
able to predict, by watching the phases of 
the moon, the accession of the disease. 
Balfour maintains that the fact of diseases 
appearing during every day of the month 
is no legitimate argument against lunar 
influence. 

iC The human body," he says, " is sub- 
ject to alterations from a thousand external 



152 On the Sanatory and 

physical circumstances as well as from many 
internal moral affections. These lay the 
foundation of disease at every period of life, 
but they do not overthrow the evidence of 
lunar influence, although they are apt to 
mislead with regard to effects that depend 
on that alone. The human body is affected 
in a remarkable manner by the changes of 
the moon, I am perfectly convinced, 
although I cannot constantly pretend to see 
the operation of the general law, nor to 
account at all times for its perturbation, and 
agree in thinking that an attention to the 
power of the moon is highly necessary to 
the medical practitioner in India." 

cc It is a fact," says Dr. Orton, <c which 
has been universally observed, particularly 
in tropical climates, that the moon has a 
great influence on the weather ; the full 



Physiological Influence of Light. 153 

and change tending to produce rain and 
storms, and the quarters being more fre- 
quently attended by fine weather." This is 
so well ascertained, and so thoroughly 
believed, at least in India, that it is nearly 
superfluous to adduce arguments or in- 
stances in support of it. On every side, 
then, we perceive the intimate connexion 
which exists between the three series of 
phenomena which have been noticed — the 
great lunar periods, disturbed states of the 
atmosphere, and the attacks of the epidemic. 
It will also be proved that the other prin- 
cipal circumstance which has been supposed 
to attend the prevalence of cholera, the de- 
pression of the barometer, is likewise pro- 
duced by the new and full moon. Dr. 
Orton says, cc Sol-lunar influence is, doubt- 
less, but one of the causes producing the 



154 On the Sanatory and 

state of the atmosphere which gives rise to 
cholera; and I have no doubt that the 
disease will often be found to make its 
appearance when the disturbing power of 
the sun and moon is least, and to subside 
when that power is at its height. General 
exacerbations of other epidemics, as well as 
of cholera, will usually be found to corre- 
spond to the moon's syzygies, and the 
remissions of the quarters." 

Dr. Kennedy bears testimony, in his 
work on Epidemic Cholera, to the influence 
of the moon. He observes, <c that the 
constitution here (India), both native and 
denizen, is assuredly under lunar in- 
fluence, or, what is the same thing, under 
the influence of the changes of weather 
which invariably accompany the changes 
of the planet." 



Physiological Influence of Light. 155 

Diemerbroeck, in his well-known treatise 
on the Plague,* when speaking of the 
epidemic of 1636, says : cc Two or three 
days before and after the new and full 
moon the disease was more violent ; more 
persons were seized at these times than at 
others, and those who were then seized 
almost all died in a very few hours. 
Nescio qua virium labefactione oppressi." 
In the dedication prefixed to this treatise, 
which is addressed to the praetor and 
consuls and the whole senate at Utrecht, 
he thus describes the nature of his own 
situation, the opportunities he had of ac- 
quiring a knowledge of the disease, and his 
object in publishing the work : — 

* "Isabrandi Diemerbroeck Montferto Trajectini, 
antehac Noviomagi, nunc Ultrajecti Medici, de Peste." 
Libri Quatuor Dissertatio, &c. Arenaci, 1646. 



1 56 On the Sanatory and 

" As in all well-constituted states it is 
the duty of every one to contribute his 
advice and assistance for the public safety, 
that by their unanimous concurrence the 
present as well as impending evils of the 
state may be averted and repelled, I con- 
ceive that I should not act improperly if, 
concerning this plague, of all diseases the 
most cruel, and more destructful than an 
enemy, I, too, should offer some salutary 
advice toward the discovery of its hidden 
nature, together with some more certain 
method of curing it. For, as in warfare, 
none can so well elude the designs of the 
enemy, or repel his attacks, as one who has 
had experience in the art of war, so none 
can more effectually resist this cruel disease 
than one who has intrepidly opposed him- 
self to its fury. This I did a long time 



Physiological Influence of Light. 157 

ago, not only in the year 1633, when a 
most violent pestilential fever, the fore- 
runner of this plague, afflicted most grie- 
vously the whole province of Gelderland, 
and principally the city of Nimeguen, where 
I was ordinary physician, and threw upon 
me so great a load of practice as hardly 
allowed me to take sustenance, but likewise, 
in 1636 and 1637, when the true plague 
raged so violently amongst the people of 
Nimeguen, and so great a number of sick 
was thrown upon my hands as to give 
me no rest or repose. Having at that 
time, with great danger, and at the risk 
of my life, investigated most inquisi- 
tively the nature of this most dreadful 
enemy, I now make public his portrait, 
delineated in this book, for the safety 
of all." 



158 On the Sanatory and 

The same writer asserts that during the 
epidemic fever which raged in Italy in 
1693, patients died in great numbers on the 
2 1 st of January, at the period of the lunar 
eclipse. But as Dr. Lardner observes, 
when recording the fact, it may be objected 
that the patients who then died in such 
numbers at the moment of the eclipse 
might have had their imaginations highly 
excited, and their fears wrought upon, by 
the approach of that event, if popular 
opinion invested it with danger. That 
such an impression was likely to prevail is 
evident from the facts which have been 
recorded. In 1654, at the time of a solar 
eclipse, such was the strong opinion enter- 
tained on this subject, that patients in con- 
siderable numbers were ordered by their 
physicians to be shut up in chambers well 



Physiological Influence of Light. 159 

closed^ warmed, and perfumed, with the 
view of escaping the injurious influence of 
the eclipse. The consternation that pre- 
vailed amongst all classes was very great, 
and such crowds rushed to the confessional, 
that the ecclesiastics found it impossible to 
exercise their spiritual vocations. 

The late Dr. James Johnson observes,* 
when alluding to the fevers of India, however 
sceptical professional men in Europe may 
be in regard to planetary influence in fevers, 
&c, it is too plainly perceptible between 
the tropics to admit of a doubt. cc I have," 
he continues, "not only observed it in 
others, but have felt it in my own person 
in India when labouring under the effects 
of obstructed liver. That this influence 
predisposes to, or exacerbates, the parox- 

* " On the Diseases of TroDical Climates." 



160 On the Sanatory and 

ysms of fever in India and other tropical 
climates is incontestably proved by daily 
observation." 

Dr. Scott, when speaking of the effect 
of sol-lunar light on the endemic and epi- 
demic diseases prevalent on the western side 
of India, says, cc The influence of the moon 
on the human body in this part of India is 
observed by every medical practitioner. It 
is universally acknowledged by the doctors of 
all colours, castes, and countries. The people 
are taught to believe in the fact in their 
infancy, arid as they grow up they acknow- 
ledge it from experience. I suppose in the 
northern latitudes this power of the moon 
is. far less sensible than in India. We here 
universally think that this state of the 
weakly and diseased bodies is much influ- 
enced by the movements of the moon. 



Physiological Influence of Light. 161 

Many people know the very day on which 
their intermittents will make their appear- 
ance ; and every full and change increases 
the number of patients of every practitioner. 
It is no argument against this influence that 
diseases appear during any day of the 
month. The human body is subject to 
alterations from a thousand circumstances, 
and from many affections of the mind. 
These lay the foundation for disease at 
any period ; but they do not overthrow 
the evidence of lunar influence, although 
they are apt to mislead with regard to that 
alone." 

Mr. Hutton, writing to Dr. Balfour from 
Calcutta, says that he has been at some 
pains during a considerable practice of some 
years at Prince of Wales Island to observe 
the effects of the moon on the prevailing 

M. 



1 6% On the Sanatory and 

diseases of that place. The diseases peculiar 
to that island are of the intermitting and re- 
mitting kind, dysenteries, diarrhoeas, liver 
complaints, and rheumatic affections. " I 
have," he adds, <c generally found the vio- 
lence of the symptoms (in the above men- 
tioned diseases) considerably increased 
during the full and change of the moon. 
I have noticed relapses to occur from the 
same cause. By keeping these facts in 
view, I have been enabled to administer the 
medicine adapted to the different diseases 
with a greater degree of certainty and pre- 
cision. " 

Dr. Moseley remarks that the greater 
haemorrhages from the lungs or those of 
plethora, like all periodical attacks of this 
kind (undisturbed in their natural course by 
peculiar circumstances), obey the influence 



Physiological Influence of Light, 163 

of the moon. Of this, he says, he has had 
many proofs. That there are not more 
authenticated by others is owing, he be- 
lieves, to the theory on which the fact 
depends not being sufficiently known to 
prevent the result escaping unnoticed. In 
another portion of his work he remarks 
that most of the patients whom he had 
attended in the spring of the year 1777 
during attacks of fever were much affected 
in the head at every new and full moon. 
He refers to the case of a man who had 
a severe attack of haemoptysis always at the 
moon's full. When speaking of the mode 
of treating these hemorrhagic conditions, 
he advises the physician to be watchful in 
every case of the kind when the moon's 
influence was considered to be greatest on 
the earth. He cites the history of a gentle- 

M 1 



164 On the Sanatory and 

man who suffered from haemorrhage of the 
lungs, who was advised to leave England 
during the winter and to reside in the south 
of France. Whilst there his attacks came 
on periodically, obeying faithfully the prin- 
cipal changes of the moon. Dr. Moseley 
considers this to be one of the most 
decisive examples of lunar influence re- 
corded in medical history. The following 
particulars of his illness deserve attentive 
consideration. 

On February 14th, 1786, when near Toulon, 
haemorrhage came on ; the moon was at its 
full on the preceding day. On February 
29th, when at Aix in Provence, he had 
another attack. There was a new moon on 
the 28th. The moon was again at its full 
on the 13th of April, and on the 15th the 
patient had another attack of haemoptysis. 



Physiological Influence of Light. 165 

A new moon appeared on the 28th of the 
same month, and on the 29th, when at 
Tain upon the Rhone, he had a relapse. 
At Chalons, in Burgundy, there was a full 
moon on the 13th of May, and on the 14th 
his haemorrhage returned. At Dijon, June 
1 1 th, when the moon was at its full, he had 
another attack. On July nth, at Paris, 
the moon was again at its full. At this 
lunar period the haemorrhage returned. 
Again, when at Yarmouth in the Isle of 
Wight, on August 9th, the moon was then 
at its full. The haemoptysis returned. Dr. 
Moseley alludes to the remarkable fact that 
the last three attacks of haemorrhage from 
the lungs came on at the instant the moon 
appeared above the horizon* 

* Dr. Moseley has pursued, in a few particulars, 
these investigations to an extreme point. I say so with- 



t66 On the Sanatory and 

Nicholas Fontana says, "that the in- 
fluence of the moon is very visible in almost 
all febrile cases. I had a good opportunity 
of observing this fact in my first voyage to 
this country (Barrackpore), in the year 1777, 
and subsequently on board the Liverpool 
East Indiaman. The ship was driven on a 
bank in the river Massuma, on the east 
coast of Africa, at a place called Behagoa 
Bay. The crew, through hard labour and the 



out intending for a moment to throw discredit on his 
general statements. He asserts as a positive fact that 
persons who live to an extreme age, invariably die at the 
new or at the full moon. After citing a number of 
instances illustrative of this opinion, he remarks, " Here 
we see the moon shines on all alike, making (as in death) 
no distinction of persons in her influence:" — 

u aquo pulsat pede pauperum tabernas 

Regumque turres." 

Hor. lib. 1, 4. 
— " A Treatise on Tropical Diseases." By B. Moseley, 
M.D. 1792. 



Physiological Influence of Light. 167 

unwholesomeness of the place, suffered much 
from epidemic bilious fever. We had 60 or 
70 patients ill out of the crew of 180. 
Every one was seized with illness, and 
several died. In the Gulf of Cambay, at 
the Nicobar Islands, at Kedgeree, in the 
River Ganges, Houghly, and on our 
return to St. Jago, one of the Cape de 
Verde Islands, where the ships went, and 
remained a certain time in the course of the 
voyage, the crew was severely and re- 
peatedly attacked with remittent and inter- 
mittent fevers. 

"I observed, and was so fully persuaded of 
the effects of the moon's changes on them 
that I took notice of the fact in a work I 
published after my return from Italy. I 
did so with the view of cautioning succeed- 
ing surgeons coming from the Mediterranean. 



1 68 On the Sanatory and 

In that country the method adopted in 
our practice was by no means fitted to 
the treatment of the acute diseases which 
Europeans were liable to between the 
tropics." 

<c Daily practice," says a well-known 
army surgeon, Dr. Millingen, cc shows that 
paroxysms of fevers and various other 
maladies are under planetary influence. 
The evening gun in our garrisons was often 
the signal of severe exacerbation in certain 
febrile cases, while the reveillee developed 
acute aggravation in others." Sydenham 
and Floyer remark that gout and asthma 
were usually ushered in after the first sleep ; 
and that during the prevalence of the 
cholera the invasion of the disease was 
noticed to occur towards daybreak. 

The authorities previously cited conclu- 



Physiological Influence of Light. 169 

sively establish that lunar influence is not to 
be viewed as a mere myth, or as an Utopian 
speculation. A host of intelligent writers 
and acute observers confirm the fact beyond 
all dispute. It will remain for me to con- 
sider, not only the evidence in favour of the 
lunar theory, but the arguments advanced 
against the hypothesis. It is only by closely 
investigating both sides of the question that 
the philosopher in search of truth will 
be enabled to arrive . at a safe deduc- 
tion. 

Before considering the effect of the moon 
upon the mind in a state of aberration it 
will be necessary to revert to the morbid 
and physiological effect of lunar light upon 
the vegetable kingdom. This has long 
been the subject of observation and specu- 
lation. Many curious and apparently inex- 



170 On the Sanatory and 

plicable facts are upon record illustrative of 
the phenomena. It will be well to refer 
to some of the more reliable data in 
connexion with this division of my sub- 
ject ; but before doing so, I would remark 
that the Druids of Gaul and Britain, who 
combined the office of physician with 
that of the priest, believing with the ancients 
that all vegetable productions, and par- 
ticularly medicinal plants, were constantly 
under planetary influence, were instructed to 
gather the far-famed mistletoe with a golden 
knife when the moon was six days old. 

It is a question whether the vervain of 
the ancients was similar to the plant which 
now bears that name. The appellation Ver- 
bena or Sagmina was given by the ancients to 
various plants used in religious ceremonies. 

The vervain, held in such high repute by 
the Romans, was gathered after libations of 



Physiological Influence of Light. 171 

honey and wine at the rising of the dog 
star, and with the left hand, and, thus col- 
lected, served for various sacerdotal and 
medicinal purposes. Its branches were em- 
ployed to sweep the temples of Jupiter ; it 
was used in exorcisms for sprinkling lustral 
water ; and, moreover, it was said to cure 
fevers, the bite of venomous reptiles, and it 
was alleged to have the virtue of allaying 
discord, and appeasing other violent passions. 
This plant so gathered was always carried in 
the hand by heralds when sent to sue for peace. 
It was called Verbenarii. When its benign 
powers were shed over the festive board, 
mirth and good temper were said to prevail. 
When speaking of the all-powerful in- 
fluence of this plant, Pliny says — 

" Nulla herba Romana nobilitatis plus habet quam 
hierabotane."* 

* Plinii, lib. 18, c. 44. 



172 On the Sanatory and 

It is stated as a fact that if peas are sown in 
the increase of the nioon they never cease 
blooming ; that if fruits and herbs are set 
during the wane of the moon, they are not 
so rich in flavour, nor so strong and healthy, 
as when planted during the increase. All 
vines should be pruned at the wane of the 
moon, says Sibley, the astrologist. He also 
asserts that pomegranates will live only as 
many years as the moon was days old when 
they were planted. In planting shrubs, if they 
are desired to shoot up straight and late, 
and to take little root, they are to be set 
when the moon is in an airy sign, and in in- 
creasing light. Flowers that are under the 
influence of the moon only open their 
blossoms at night, whilst those that are 
peculiarly under the government of the sun 
open every morning when it begins to rise, 



Physiological Influence of Light. 173 

and close in the evening when he sinks 
below the horizon. M. Auguste de Saint- 
Hilaire states, that in Brazil, cultivators 
plant during the decline of the moon, all 
vegetables whose roots are used as food ; 
and, on the contrary, they sow during the 
increasing moon the sugar-cane, maize, rice, 
beans, &c, and in general those which bear 
the food upon their stocks- and branches. 
Experiments, however, were made and 
reported by M. de Chanvalon, at Martinique, 
on vegetables planted at different times in 
the lunar month, and no appreciable diffe- 
rence in their qualities was discovered. 
There are some traces of a principle in the 
rule adopted by the South American 
agronomes, according to which they treat 
the two classes of plants distinguished by 
the production of fruit on their roots or on 



174 ® n the Sanatory and 

their branches differently ; but there are 
none in the European aphorisms. The 
directions of Pliny are still more specific : 
he prescribes the time of the full moon for 
sowing beans, and that of the new moon for 
lentils. cc Truly/' says M. Arago, cc we 
have need of a robust faith to admit, with- 
out proof, that the moon, at the distance of 
240,000 miles, shall, in one position, act 
advantageously upon the vegetation of 
beans, and that, on the opposite position, 
and at the same distance, she shall be pro- 
pitious to lentils." The wise husbandman 
is said to prune his vines in obedience to 
certain phases of the planet. It is a maxim 
amongst gardeners that cabbages and lettuces 
which are desired to shoot forth early, 
flowers which are to be double, trees which 
it is desired should produce early ripe 



Physiological Influence of Light. 175 

fruit, should severally be sown, planted, 
and pruned during the decrease of the 
moon ; and, on the contrary, that trees 
expected to grow with vigour should 
be sown, planted, grafted, and pruned 
during the increase of the moon. These 
opinions Dr. Lardner considers to be 
altogether erroneous. The increase or de- 
crease of the moon, he maintains, has no 
appreciable influence on the phenomena of 
vegetation ; and the experiments and obser- 
vations of several French agriculturists, and 
especially of M. Duhamel du Monceau, 
have, he observes, clearly established this 
fact. 

Mantanari has referred to physical causes 
for an explanation of the alleged lunar 
influence upon plants. During the day, he 
says, the solar heat augments the quantity 



t;6 On the Sanatory and 

of sap which circulates in plants, by increas- 
ing the magnitude of the tubes through 
which the sap moves, while the cold of the 
night produces the opposite effect by con- 
tracting these tubes. Now, at the moment 
of sunset, if the moon be increasing, it will 
be above the horizon, and the warmth of 
its light would prolong the circulation of the 
sap ; but, during its decline, it will not rise 
for a considerable time after sunset, and the 
plants will be suddenly exposed to the un- 
mitigated cold of the night, by which a 
sudden contraction of leaves and tubes will 
be produced, and the circulation of the sap 
as suddenly obstructed. This explanation 
does not satisfy Dr. Lardner, who remarks, 
that if it be admitted that the lunar rays 
possess any sensible calorific power, this 
reasoning might hold good, but it will have 



Physiological Influence of Light, 177 

very little force when it is considered that 
the extreme change of temperature which 
can be produced by the lunar light does 
not amount to the thousandth part of a 
degree of the thermometer ! Upon this 
point, however, philosophers are at variance. 
The lunar rays have, according to the ex- 
perience of practical men, a decided calorific 
effect. 

The gardeners of Paris assured Arago that 
in the months of April and May they found 
the leaves and buds of their plants, when 
exposed to the full moon in a clear night, 
actually frozen , when the thermometer in the 
atmosphere was many degrees above freezing- 
point. He mentions these facts as proving 
that the moon's rays have a frigorific power, 
but that the largest speculums directed to 
the moon produced no such indications on a 

N 



178 On the Sanatory and 

thermometer placed in their focus.* Dr. 
Howard, of Baltimore, has affirmed that on 
placing a blackened upper ball of his 
differential thermometer in the focus of a 
thirteen-inch reflecting mirror opposed to 
the light of the full moon, the liquor sank, 
in half a minute, eight degrees ! Though 
the surface of the full moon exposed to us 
must necessarily be very much heated, says 
Sir J. Herschel, possibly to a degree much 
exceeding that of boiling water — yet we 
feel no heat from it, and even in the focus 
of large reflectors it fails to affect the 
thermometer. No doubt, therefore, its 
heat (conformably to what is observed of 
that of bodies heated below the point of 
luminosity) is much more readily absorbed 
in traversing transparent media than direct 

* Ferguss. " Bull. Univ." 1827, p, 383. 



Physiological Influence of Light, 179 

solar heat, and is extinguished in the upper 
regions of our atmosphere, never reaching the 
surface of the earth at all. Some proba- 
bility is given to this by the tendency to 
disappearance of clouds under the full 
moon, a meteorological fact (for as such we 
think it fully entitled to rank), for which 
it is necessary to seek a cause, and for which 
no other rational explanation seems to offer. * 
Cases of sudden death and profound 
coma are recorded as the effect of an im- 
proper and prolonged exposure to the 
intense light of the full moon. Sailors have 
been found dead on deck after sleeping 
under the moon's rays. It is also said that 
convulsions, apoplexy, epilepsy, and in- 
sanity, sensations of oppression in the head, 
inertness and heaviness of the senses, have 
* Outlines of Astronomy, pp. 261, 2. 1849. 
N-3 



i8o On the Sanatory and 

arisen from the same cause. Plutarch 
observes : — cc Everybody knows that those 
who sleep abroad under the influence of the 
moon are not easily awakened, but seem 
stupid and senseless."* In India, death has 
occasionally been known to arise from what 
is termed a coup de lune> or stroke of the 
moon ; and in Egypt, blindness has often 
been produced in persons who have impru- 
dently fallen asleep with their faces exposed 
to intense lunar light. Does not Edgar 
Allan Poe refer to this morbid effect of the 
moon's rays in the following passage ? — 

" 'Neath blue bell or streamer, 
Or tufted wild spray, 
That keeps from the dreamer 
The moonbeam away."f 

* Plut. " Symp." B. 3. 

f "Al Aaraaf." Tycho Brahe suddenly discovered in the 
heavens a star which attained in a few days a brilliancy sur- 



Physiological Influence of Light. 181 

Dr. Madden mentions that the Arabs 
attribute a morbid influence to the moon, 
and think it causes ophthalmia and catarrh. 
He thought there was some influence from 
it in the desert beyond the common damp- 
ness of the night.* 

The questions that naturally occur to the 
mind in reference to this interesting inquiry 
are, whether the morbid phenomena alleged 
to result from the moon's rays are dependent 
upon the mere intensity of lunar light , or are 
to be considered as the effect of some specific 
influence in the nature of the light itself? 
Let me consider the first question. It is an 
admitted fact that the light of the full moon 



passing that of the planet Jupiter, and then as quickly 
disappeared ! This phenomenon gave origin to the poem 
referred to. 

* " Travels in Turkey." 



1 82 On the Sanatory and 

is at least 300,000 times more feeble than that 
of the sun. According to Humboldt, the 
mean distance of the earth from the sun is 
12,032 times greater than the earth's dia- 
meter, therefore 20,682,000 German or 
82,728,000 English geographical miles. The 
mean distance of the moon from the earth is 
51,800 German or 207,200 English geogra- 
phical miles.* 

It is said that the solar light reflected from 
the surface of the moon is in every zone 
fainter than the solar light reflected in the 
daytime from a white cloud. f 

When estimating the intensity of lunar 
light, Sir John Herschel affirms, that in the 

* Cosmos, 
f Sir J. Herschel says that it appears to be placed 
beyond a doubt that the moon acts directly as a magnet 
on the earth's magnetism, producing periodical fluctuations 
in the latter of extremely small amount. 



Physiological Influence of Light. 183 

southern hemisphere the moon is 27,408 
times brighter than a Centauri, which is third 
in brilliancy of all the stars. In our own cli- 
mate the light of the moon is said to be 3000 
times greater than that of the planet Venus. 
Planetary light requires fourteen minutes to 
cross the earth's orbit. According to Bradley, 
the light of the sun takes eight minutes to 
reach the earth. Reckoning the mean dis- 
tance of the sun to be 94,879,956 miles from 
the earth, it follows that light traverses 
the air with a velocity of about 200,000 
miles per second.* Robins states that a 

* One hundred and eighty thousand miles per second 
according to Herschel's calculation, that is 901,000 times 
faster than sound, which travels at the rate of 1090 feet per 
second, or nearly thirteen miles in a minute. Were the sun 
and the earth connected by an iron bar, 1074 days, or 
nearly three years, must elapse before a force applied at the 
sun could reach the earth. With a bar of tin, nearly seven 
years would be necessary. A writer in the " Quarterly Re- 



184 On the Sanatory and 

twenty-four-pounder with a common charge 
of powder discharges its ball with an initial 
velocity equal to 1600 feet per second. If 
such a ball were to continue its velocity 
undiminished, it would require about ten 
years to traverse a span, which the light of 
the heavenly bodies pervades in eight 
minutes ! 

Humboldt, when speaking of this subject, 
remarks : — <c When taking lunar distances 
from the sun for determinations of geogra- 



view" has placed this remarkable property of matter in a 
popular and paradoxical aspect, by imagining Titan and 
Saturn placed in opposite points of the orbit of the planet 
which bears the name of the latter, and their ancient com- 
bats being resumed with weapons of earthly fabric, the deadly 
blow dealt by the former would not slay its victim till 
after the lapse of fifty-two years ; and if, one year before 
this event, Saturn should aim a mortal thrust at his 
antagonist, it could not prove fatal till fifty-one years after 
his own death! 



Physiological Influence of Light, 185 

phical longitude, it is not unfrequently 
found difficult to distinguish the moon's 
disk amongst the more intensely illuminated 
cumuli. On mountains between 13,000 and 
17,000 feet high, where in the clearer moun- 
tain air only light, feathery, cirrous clouds 
are to be seen, I found it much easier to 
distinguish the moon's disk ; both being 
cirrous, from its slighter texture, reflects 
less of the sun's light, and the moon loses 
less in passing through the thin atmospheric 
strata." The ratio of the intensity of the 
sun's light to that of the full moon deserves 
further investigation, as Bouguer's generally 
received determination, 3 00 ' 000} differs so 
strikingly from the indeed more improbable 
one of Wollaston, 800 ' 000 . Wollaston's 
comparison of the light of sun and moon, 
made in 1799, was based on the shadows 



1 86 On the Sanatory and 

cast by wax-light, while in the experiments 
with Sirius, in 1826-27, images reflected 
from a glass globe were employed. The 
earlier assigned ratios of the intensity of 
solar light as compared to that of the moon 
differ very much from the results here 
given. Michel and Euler, proceeding from 
theoretical grounds, have respectively con- 
cluded 450,000 and 374,000 to 1. Bou- 
guer, from measurements of the shadows of 
wax-lights, had even made it only 300,000 
to 1. 

I think, after duly weighing the above 
facts, we must dismiss from the mind the 
impression that the intensity of the light of 
the moon, as compared to that of the sun, 
has any relation to the supposed morbid 
effect of lunar light. 

I proceed, in the next place, to the con- 



Physiological Influence of Light. 187 

sideration of the questions, whether the 
alleged morbid effect of lunar rays is attri- 
butable to something specific in the com- 
position of the light itself ; and secondly, 
whether the supposed abnormal influence of 
the moon is not altogether owing to certain 
barometrical variations and meteorological 
phenomena consequent upon the phases 
or position of the planet. Is there 
anything specific in the composition of 
lunar light ? 

According to numerous observations 
which Arago made with his polariscope, 
the moon's rays contain 'polarized light 
which carbonizes , and is therefore antago- 
nistic to the sun's rays, which oxygen- 
ate. The polarization of light was not dis- 
covered until five years before the death of 
Huyghens, viz., in 1690. It has, however, 



i88 On the Sanatory and 

been stated that the phenomenon was recog- 
nised in 1665, by Grimaldi and Hooke. 

When a polarized ray is passed through 
a thin slice of transparent substance, its 
effect is said to be most remarkable. " Its 
whole molecular constitution/' says Mr. 
Hunt, cc appears revealed, as if by the touch 
of a magic wand. The surfaces of many 
substances, such as thin films of sulphate of 
lime or mica, become painted with the most 
beautiful colours. By turning the plate of 
the polariscope round, these can be made to 
dissolve or reappear in an exceedingly sin- 
gular manner. Rings of the most charming 
colours are seen in some substances, and 
these are marked with a figure resembling a 
Maltese cross in black and white. 

Polarized light has been used by chemists 
for the purposes of making subtle analyses of 



Physiological Influence of Light. 189 

certain articles of food. M. Biot has applied 
the rays of polarized light to sugar with the 
view of ascertaining the existence of adulte- 
rations. It is easy by means of the polari- 
scope to distinguish between sugar made 
from beet-root and that manufactured from 
the sugar-cane.* 

What is polarized light? Sir David 
Brewster thus lucidly explains the pheno- 
menon : When the ray of light falls on a 
transparent body, so as to be reflected from 
it, it is modified or affected in such a manner 
by this reflection, that upon meeting a second 
transparent body, it will either be reflected 
or not, according to the side which it pre- 
sents to it. It will be reflected if it fall 
upon that body on either of the opposite 
sides, but will not be reflected if it fall upon 

* Hunt on Light. 



190 On the Sanatory and 

either of the other two, at right angles to 
the former. Thus, suppose the ray, after 
being modified by the first transparent re- 
flector, presents itself to the second, so as to 
be reflected, and call the side of the ray, on 
which it meets the second reflector, on the 
north side ; if the second reflector is turned 
round, so that the east side of the ray meets 
it, there will be no reflection, and in like 
manner it will be reflected on the south and 
not on the west sides respectively. The 
same modification, whatever it may be, 
prevents the ray from being doubly refracted, 
by passing through Iceland crystal, which it 
meets on two of its opposite sides, but per- 
mits it to be doubly refracted by meeting 
the crystal on the two other sides. And 
this modification, with respect to double 
refraction, may be impressed upon the ray 



Physiological Influence of Light, 191 

by a first double refraction, as well as by- 
reflection from a transparent body. But 
where the modification is produced by reflec- 
tion, it is most complete at one particular 
angle of incidence, which varies in different 
transparent substances. 

Now, the existence of this phenomenon 
is certain ; it is a fact that a change takes 
place in the ray by the operation of the 
first transparent body ; it is a fact that this 
change has some kind of reference to the 
four sides of the ray, and affects those sides 
at right angles to each other differently. 
The observers of these appearances have 
explained them, by supposing that each 
particle of light has its adjacent sides en- 
dowed with opposite properties, and that 
the first reflecting, or double refracting 
body, turns or arranges all the particles of 



192 On the Sanatory and 

light in a ray, in such a manner that their 
similar sides are presented in the same di- 
rection to the second body. Now this 
arranging or turning of the particles, or 
this change operated by the first body upon 
the ray, whatever it may be, is termed, 
from analogy to the phenomena of mag- 
netism — polarization.* 

Having cursorily referred to two modes 
of explaining the morbid phenomena of 
moonlight, I have yet to consider the most 
rational and philosophic theory of lunar 
influence propounded — viz., the effect of 
the moon's position upon the wind, temper a- 
ture> and rain, three meteorological con- 
ditions universally admitted to play an 
important part in the origin, spread, and 
modification of disease. It has been a 

*"On Optics," by Sir David Brewster. 



Physiological Influence of Light. 193 

vexed question with natural philosophers, 
whether the barometer is decidedly influenced 
by the phases of the moon. The facts 
illustrative of this point are too significant 
to justify a doubt upon the question. 

A remarkable correspondence between 
the phases of the moon and certain states 
of the barometer has been observed by 
Luke Howard. This coincidence, he main- 
tains, consists of a depression of the baro- 
metrical line on the approach of the new 
and full moon, and its elevation on that of 
the quarters. In above thirty out of fifty 
lunar weeks in one year, the barometer was 
found to have changed its general direction 
once in each week, in such a manner as to 
be either rising or at its maximum for the 
week preceding and following about the 
time of each quarter, and to be either fall- 
o 



194 On the Sanatory and 

ing, or at its minimum, for the two weeks 
about the new and full. It is remarkable 
that the point of greatest depression during 
the year — viz., 28*67, was about twelve 
hours after the new moon on the 8th of 
November, and that of the greatest and 
extraordinary elevation of 30*89, on the 7th 
of February, at the time of the last quarter. 
The variation from this coincidence seemed 
to be owing to an evident perturbation of 
the atmosphere. These observations were 
confirmed by observations made for ten 
years in the Royal Society's apartments. 
Mr. Howard supposes, therefore, that the 
joint attractions of the sun and moon at the 
new moon, and the attraction of the moon 
predominating over the sun's weaker attrac- 
tion at the full, tend to depress the barometer 
by taking off the gravity of the atmosphere, 



Physiological Influence of Light. 195 

as they produce a high tide in the waters by- 
taking off from their gravity ; and again, 
that the attraction of the moon being dimi- 
nished by that of the sun at her quarters, 
this diminution tends to make a high baro- 
meter, together with a low tide, by per- 
mitting each fluid to press with additional 
gravity on the earth. It is demonstrated 
a priori on the principles of the Newtonian 
philosophy, that the air ought to have its 
tides as well as the ocean, though in a degree 
as much less perceptible as its gravity.* If 
this observation were strictly true, and the 
tides of the atmosphere were to those of the 
sea as the specific gravity of air is to that of 
water, the aerial tides must be extremely 
small, for the weight of air is very trifling 
compared to that of water. But it is known 

* " Encyclopaedia Britannica." 
O 2 



ig6 On the Sanatory and 

that the height of the tides of the sea bears 
some proportion to the extent of the sea, 
uninterrupted by land, and to its depth. On 
both these accounts we should expect that 
the atmosphere would be more influenced 
by the moon's attraction than the sea, for 
it is vastly deeper and more extensive 
than the sea, and entirely unconfined. 

Signor Tolado found that a greater eleva- 
tion of the barometer takes place at the 
quarters than at the syzygies ; it is less 
when the moon is in the northern signs than 
when in the southern. The mean diurnal 
height, which corresponds to the Tropic of 
Cancer, is less by a quarter of a line than 
that which corresponds to the Tropic of 
Capricorn. It is one-sixth of a line less at 
the moon's perigee than at her apogee, and 
one-tenth of a line less at the syzygies than 



Physiological Influence of Light, 197 

at the quarters ; and there are vacillations in 
the mercury when the new or full moon 
corresponds to the apogean or perigean 
points. He found, also, that the perigee, 
the new and full moon, and the northern 
lunistice are favourable to bad weather ; 
whilst the apogee, the quadratures, and the 
southern lunistice are more favourable to 
good weather. 

Pere Cotte, from observations of thirty- 
five years, found that the barometer had a 
tendency to descend at every new and full 
moon, and to ascend at the quarterly periods. 
He likewise found that the perigee and 
northern declination depressed the barometer, 
whilst the apogee and southern declination 
had the opposite effect.* Mr. L. Howard 

* Orton, on " Epidemic Cholera," p. 222 ; and " Lec- 
tures on Meteorology," by G. Luke Howard. 



On the Sanatory and 



has satisfactorily established, that the moon's 
position, operating by the common effects 
of the attraction of gravitation, influences 
alike the course of the variable winds, the 
daily variations of the temperature, and the 
rain of any year ; but not in every year 
alike, there being a constant periodical varia- 
tion of the variation itself.* 

* M. Kraszewski, of Romano w (as quoted by Andrew 
Steinmetz in his work on " Sunshine and Showers"), has 
decided, from a long series of observations: — " i. That 
63 times in 100 the weather changes to bad when the 
moon crosses our equator. 2. When the moon's declina- 
tion is north, bad weather occurs more frequently than 
when it is south. 3. When the moon is in its perigee, and 
at the equator, bad weather occurs 67 times in too ; when 
in its apogee, but still at the equator, there is bad weather 
63 times in 100 ; and 4. Generally the moon near the 
equator determines bad weather in the same proportion." 



Physiological Influence of Light. 199 



PART III. 



ON THE ALLEGED INFLUENCE OF THE 
MOON ON THE INSANE. 



The recognised phrase, lunatic, is based on 
the hypothesis that the moon exercises a 
decided effect upon the insane, and modifies 
various forms of morbid intellect which do 
not amount to actual insanity : hence origi- 
nated the well known legal term, fC lucid 
interval."* It was supposed that during 

* Lunatic, according to ancient legal dicta, is one whose 
imagination is influenced by the moon and has lucid in- 
ervals : " Lunaticus, qui gaudet lucidis interval/is." 

Sir W. Blackstone defines a person who is non compos 
mentis to be one " who has had understanding, but by 



200 On the Sanatory and 

paroxysms of mental derangement, the pa- 
tient was liable to periods of lucidity or 
mental repose, caused by the various phases 
of the moon. Acting on this assumption, 
human life was often made contingent 
upon a satisfactory solution of the ques- 
tion, was or was there not a lucid interval 
when a particular crime was committed? 
The transmission also of property to a 
vast amount often depended on the reply 
to a similar interrogatory relating to a 
period when a certain testamentary dispo- 
sition was made. A lucid interval legally 
implies a clear and distinct freedom of the 
mind from all delusions ; in other words, 

disease, grief, or other accident, has lost the use of his 
reason ; but that a lunatic is indeed properly one who 
hath lucid intervals, sometimes enjoying his senses, and 
sometimes not, and that frequently depending upon the 
change of the moon" — " Commentaries." 



Physiological Influence of Light. 20 1 

such an intelligent repose and restoration of 
the intellectual powers as to enable the 
person mentally disordered to discriminate 
accurately between right and wrong ; thus 
constituting him morally and legally respon- 
sible for his conduct, quoad any criminal act 
of which he may have been guilty, or render- 
ing him competent to exercise a sound 
memory, judgment, and reflection relating 
to any testamentary act he has, during a 
questionable condition of mind, been called 
upon to execute. 

Into the judicial view of this important 
and vexed question it would be foreign to 
my purpose to enter.* I therefore propose 

* The rule of law upon this subject is, that all acts 
done during a lucid interval are to be considered done by 
a person perfectly capable of contracting, managing, and 
disposing of his affairs. This has most frequently been a 
question in wills ; and the. Ecclesiastical Courts, which 



202 On the Sanatory and 

confining my remarks to the main point at 
issue,, viz., is it satisfactorily established that 

first promulgated the rule, adopted it from the Roman 
law, il Furiosi autem si per id tempus fecerint testamentum 
quo furor eorum intermissus est,jure testatum esse videntur." 
— (Justin. Inst. lib. it, tit. 12, s. 1). 

A lucid interval consists not in a mere cessation of the 
violent symptoms of a disorder ; neither is it a cooler 
moment, an abatement of pain or violence, relaxation from 
a higher state of torture, or the relief of a mind from ex- 
cessive oppression. 

But an interval is that in which the mind, having thrown 
oft the disease, has recovered its general habit. The party 
must be capable of forming a sound j udgment of what he 
is doing ; and his state of mind should be such, that any 
indifferent person would think him able to manage his own 
affairs. 

M. D'Aguesseau, when pleading before the Parliament 
of Paris, observed — u That to constitute a lucid interval, 
there must not be a superficial tranquillity or shadow of 
repose ; but on the contrary, a profound tranquillity, a 
real repose; there must be, not a mere ray of reason, which 
only makes its absence more apparent when it is gone, not 
a flash ot lightning, which pierces through the dai kness 
only to render it more gloomy and dismal, not a glimmer- 



Physiological Influence of Light. 203 

the moon has any perceptible effect upon 
the insane ? 

I should be giving but an imperfect 
sketch of the literature of this subject if I 
were not to refer to the fact that the poets, 
as well as philosophers and medical writers 
of ancient and modern times, have not failed 
to countenance by the authority of their 
genius the popular belief in the influence 
of the moon not only on the bodily health, 



ing which unites the night to the day ; but a perfect light, 
a lively and continued lustre, a full and entire day, inter- 
posed between the two separate nights, of the fury which 
precedes and follows it ; and, to use another image, it is not 
a deceitful and faithless stillness, which follows or forebodes 
a storm, but a sure, steadfast tranquillity for a time, a real 
calm, a perfect serenity ; in fine, without looking for so 
many metaphors to represent our idea, it must not be a 
mere diminution, a remission of the complaint, but a kind 
of temporary cure, an intermission so clearly marked, as in 
every respect to resemble the restoration of health." 



204 On the Sanatory and 

but on the passions, and especially on the 
mind when in a state of disorder. Most of 
our great dramatic and epic poets have 
embodied in their immortal creations this 
idea. The works of Shakspeare, Spenser, 
Beaumont and Fletcher, Ben Jonson, Mil- 
ton, Byron, and Shelley are replete with 
passages of exquisite beauty in relation to 
this subject. Our own immortal bard, 
whose marvellous apprehension and pro- 
found knowledge of the mind, intuitive 
insight into the subtle workings of the 
human heart and passions, and intimate 
acquaintance with nearly every branch 
of knowledge, department of science, art, 
and philosophy, placed him like a bright 
and brilliant constellation on a giddy emi- 
nence, far above the rest of mankind, 
has pointedly alluded to the moral and 



Physiological Influence of Light, 205 

mental influence of the moon on the heart 
and intellect. In the "Twelfth Night/' 
Viola apostrophizes Olivia as a 

" Most radiant, exquisite, and unmatchable beauty." 

" I heard you were saucy at my gates," replies Olivia, 
" and allowed your approach, rather to wonder at you than 
to hear you. If you be not mad, begone; if you have reason, 
be brief ; 'tis not that time of the moon with me y to make 
one in so skipping a dialogue" 

Again, in the play of cc Antony and Cleo- 
patra/' Enobarbus, after entering Caesar's 
camp, thus appeals to the moon : — 

li Be witness to me, thou blessed moon ! 
When men revolted shall upon record 
Bear hateful memory, poor Enobarbus did 
Before thy face repent !" 

After which, he adds, addressing the 
moon, previously to expressing his deep 
contrition for his revolt against Antony — 



2o6 On the Sanatory and 

" O sovereign mistress of true melancholy y 
The poisonous damp of night dispunge upon me ; 
That life, a very rebel to my will, 
May hang no longer on me." 

In cc Othello/' after the death of Desde- 
mona^ when Emilia enters the chamber to 
announce the foul murder of Roderigo by 
the hand of Cassio, the Moor, crushed to 
the earth by an accumulation of horrible 
misfortunes, exclaims in the agony of his 
soul, and in the bitterness of wild despair — 

(i It is the very error of the moon y 
She comes more near the earth than she was wont, 
And makes men mad." 

In cc King Richard the Third/' the 
Queen, after rushing whilst in a state of 
profound distraction, into the presence of 
the Duchess of York to announce the death 
of the King, passionately exclaims — 



Physiological Influence of Light. 207 

" Give me no help in lamentation, 
I am not barren to bring forth laments ; 
All springs reduce their currents to mine eyes, 
That J, being govern 'd by the <zvafry moon. 
May send forth plenteous tears to drown the world ! " 

Milton frequently alludes, in kC Paradise 
Lost," to the morbid effect of the moon. 
He speaks of 

Ci Demoniac frenzy, moping melancholy, 
And moon-struck madness" 

In Ben Jonson's cc Alchemist," Tribula- 
tion says — 

u But how long time, 
Sir, must the saints expect ?" 

To which Subtle responds — 

" Let me see, 
How's the moon now ? Eight, nine, ten days hence 
She will be silver potate ; then three days 
Before to citronize, — some fifteen days."* 

Apart altogether from the astrological 

* Act iii. scene 1. 



2o8 On the Sanatory and 

ideas prevalent in former times as to the 
specific influence of the moon on the in- 
sane, it is not difficult to understand why 
this notion should have found favour among 
learned, scientific, and experienced men. 
It must be admitted that there is much of 
the phenomena of insanity yet mysterious 
and inexplicable. I refer particularly to 
the remarkable periodicity that in many 
cases accompanies the progress of this 
disease. It is commonly supposed to be 
difficult physiologically and pathologi- 
cally to explain why such distinct periods 
of apparent recovery should take place 
during paroxysms of acute insanity. Cases 
occur in which a patient is outrageously in- 
sane one day, and to ordinary observers 
sane the next ; furiously mad one week, 
calm and composed the next ; mischievously 



Physiological Influence of Light. 209 

deranged in the mind for about a month or 
six weeks, and then for an equal duration 
in a sane state of intellect. Not only 
are these lucid intervals or remissions often 
noticed during the existence of the mental 
malady but the character of the affection also 
undergoes singular changes and modifications. 
A patient recently under my care was sad 
and depressed for one or two days, and 
then for a similar period was in an exalted 
and happy state of mental disorder. 

Pinel knew a patient who became insane 
regularly every year. This illness lasted 
for three months, and terminated favou- 
rably towards the middle of the summer. 
Another patient was annually subject to 
paroxysms of maniacal furor for a period of 
fifteen days, but was in the perfect pos- 
session of his reason for the remaining 
p 



210 On the Sanatory and 

eleven months and a half. In another 
case this physician noticed the attack of 
insanity to come on every third day, being 
in this respect analogous to the periodicity 
observed in tertian intermittent fevers. 

In cases of acute melancholia, associated 
with a suicidal feeling, the attacks often 
come on periodically. For a week or ten 
days the desire to commit suicide will pre- 
vail, and then the insane craving for self- 
destruction will suddenly vanish. A patient 
may be strongly bent on suicide in the 
morning and have no inclination to destroy 
himself later in the day. 

Drunken madness or dipsomania , as it is 
termed, in some cases comes on periodically. 
Bruhl-Cramer cites an instance in which vio- 
lent paroxysms of intemperance occurred re- 
gularly every four weeks at the new moon. 



Physiological Influence of Light. 211 

Most, another authority, confirms this fact. 
In Henke's Zeitschrift fur Staatsarznei- 
kunde, a case is related of monthly periodical 
attacks of drunkenness, each attack occu- 
pying eight days. The patient was ill in 
this irregular way for seven years. Friedreich 
says this periodicity is peculiarly characteristic 
of attacks of dipsomania. In some cases 
the paroxysms come on with great regu- 
larity once in two, three, and four weeks. 
In other instances several months intervene 
between the attacks. Occasionally the pa- 
tient is known to have seizures of dipso- 
mania regularly every second, third, and 
fourth year. Guislain mentions the case of 
a woman whose temperate lucid intervals 
extended over a period of four years. At 
the end of this time the drunken madness re- 
turned, lasting some time with great violence. 
p a 



212 On the Sanatory and 

Esquirol, Pinel, Falret, Cerise, Brierre de 
Boismont, Baillarger, Foville, Calmeil, and 
other celebrated French authorities, cite simi- 
lar illustrations of the remarkable periodicity 
so often associated with mental disorders. 

Without giving the details of cases that 
have come under my own personal observa- 
tion, I may in general terms state that I 
have frequently observed the phenomenon 
referred to among insane patients. In this 
respect, insanity in no way differs from 
the periodicity which is so characteristic of 
many forms of general disease ; such as inter- 
mittent fevers, gout, tic doloureux, cephalal- 
gia, neuralgia, epilepsy, and other affections 
in which the nervous system is implicated. 

Is the periodicity alluded to as often 
accompanying some types of insanity ex- 
plicable apart from the hypothesis of lunar 



Physiological Influence of Light. 213 

influences ? I think there can be but one 
opinion on this subject. The remarkable 
remissions that occur during attacks of men- 
tal derangement depend upon a variety of 
causes, such as the removal, by appro- 
priate treatment, of temporary congestion 
of the brain, and irregularity of the cerebral 
circulation; or the lucid moments may be the 
effect of paying strict attention to dietetic 
regimen, condition of the digestive organs, 
bowels, liver, skin, and kidneys, or be the 
result of carefully isolating the patient for 
a time from all mental worry and excitement. 
Pinel is . of opinion that the periodicity 
occasionally associated with insanity is more 
dependent upon an undue indulgence of the 
angry passions, intemperance in drinking, 
inanition ; or mental agitation caused by 
a remembrance of . the original exciting 



214 On the Sanatory and 

cause of the malady, than by direct lunar 
influences. From a general examination 
Pinel made during the second year of the 
republic, of the patients confined in the 
Bicetre, he found only fifty-two who were 
subject to paroxysms of insanity at irregular 
periods, and only six whose attacks were 
characterized by a regular intermission. 

In considering this subject, it. is not my 
intention to 'quote the somewhat fabulous 
cases alleged to be illustrative of the moon's 
influence on the mind, recorded by ancient 
and modern writers on astrology. Before, 
however, referring to the opinions of the 
great Roman authority in medicine, I think 
the following facts, when viewed in relation 
to the subject under discussion, worthy of 
notice : Aristotle records the case of an 
innkeeper at Tarentum who, although able 



Physiological Influence of Light. 215 

to attend to his business during the day, 
became insane soon after the setting of 
the sun ! Bouillon cites the case of a 
woman who lost the use of her senses at 
sunset, but who recovered them at day- 
break ! Sauvage refers to a woman who 
became maniacal whenever the sun was at its 
zenith ! An ineffectual attempt was made 
to cure her of the malady by various strata- 
gems, such as keeping her in a dark room 
and deceiving her as to the hour. 

In the chapter treating of Insanity, en- 
titled cc Be tribus insanice generibus" Celsus 
makes no special allusion to the influence of 
the moon on the insane. In the fourth 
chapter of his first book, commencing cc De 
suibus caput infirmurn est^ he says c Cui 
caput infirmurn est y is, si bene concoxerit, 
leniter perfricare id mane manibus suis debet ; 



2i6 On the Sanatory and 

nunquam id, si fieri potest, veste velar e; ad 
cut em tondere : utile que luna" He then 
adds the following advice, by which it is 
clear that he viewed with grave suspicion 
the injury likely to arise from an injudicious 
exposure to the influence of the moon, es- 
pecially cc before her conjunction with the 
sun." cc Utileque lunam vitare, maximeque 
ante ipsurn luna solisque concur sum ; sed nus- 
quam post cibum" 

Do the words cc caput infirmum " mean 
insanity in the right and generally received 
acceptation of the term, or do they imply 
a mere weakness of intellect so often ob- 
served after attacks of ordinary fever, and 
seen to follow other bodily diseases ? The 
latter construction appears to be the one 
most generally adopted. 

The late Dr. Haslam considered it more 



Physiological Influence of Light, % 1 7 

than probable that the origin of the idea of 
the moon exercising an influence on the 
insane may be thus traced and explained : 
The phases of the moon, and particular 
female indispositions, are alleged to cor- 
respond. The terms used to designate 
them, have reference to the time when 
both are completed. Insanity and epilepsy 
are often connected with these conditions, 
and suffer an exacerbation at the time when 
they occur or ought to take place. If, there- 
fore, the ailment referred to in an insane 
person should be coincident with the full of 
the moon, and the mind should then be more 
violently disturbed, the recurrence of the 
same state may be naturally expected at the 
next full moon. Such has been the preva- 
lence of this opinion, that when patients were 
brought in former times to Bethlehem Hos- 

\ 



218 On the Sanatory and 

pital, especially from the country, their friends 
have generally stated them to be worse at 
some particular change of the moon, and of 
the necessity they were under, at those times, 
of having recourse to severe coercion. Some 
of these patients, after recovering, have stated 
that the overseer or master of the work- 
house himself has frequently been so much 
under the dominion of this planet (keeping 
steadily in mind the old maxim, cc venienti 
occurrite morbo"), that, without waiting for 
any display of increased turbulence on the 
part of the lunatics, he has barbarously 
bound, chained, flogged, and deprived them 
of food, according as he discovered the 
moon's age by the almanack! 

To ascertain how far this opinion was 
founded on fact, Dr. Haslam kept, during 
more than two years, an exact register of 



Physiological Influence of Light. 219 

the numerous cases under his care, but with- 
out finding, in any instance, that the aberra- 
tions of the human intellect were influenced 
by the phases of the moon. 

As insane persons, especially those in a 
furious state, are but little disposed to sleep, 
even under the most favourable circum- 
stances, they will be still less so when 
the moon shines brightly into their apart- 
ments.* 

Dr. J. B. Woodward, late superintendent 
of the State Hospital, at Worcester, Massa- 
chusetts, at the suggestion of one of the 
most scientific men in New England, com- 
menced a table of observations on the in- 
fluence of this planet upon the paroxysms 
and deaths of the insane, and, after much 

* Haslam's ft Observations on Madness and Melan- 
choly," pp. 214 — 217. London: 1809. 



izo On the Sanatory and 

time devoted to the subject, says : — fC These 
facts and coincidences we leave for the 
present, with the single remark, that no 
theory seems to be supported by them, 
which has existed either among the ignorant 
or wise men who have been believers in the 
influence of the moon upon the insane." 

The report from which the preceding 
passage is quoted then adds : — 

<c Many patients are certainly more exci- 
table and restless in pleasant moonlight nights 
than in dark and gloomy weather ; but this 
would seem to be occasioned by the real or 
imaginary sight of objects in or without 
the building, such as men, trees, animals, 
&c, or the motion, perhaps, of the passing 
clouds. An opinion, however, that has 
existed for so long a period, which has spread 
so extensively, and which, in this country, 



Physiological Influence of Light. 221 

is familiar as c household words/ deserves to 
be carefully examined ; for it is important to 
disprove error as well as to establish truth. 

cc Weak and timid females are sometimes 
alarmed and much agitated during the con- 
tinuance of lightning and thunder ; but as 
a general thing, we have not observed the 
insane to be much disturbed on such occa- 
sions." 

In the preceding passages I have endea- 
voured accurately to record the opinions of 
various accredited medical authorities adverse 
to the theory of the moon's influence upon the 
insane. 

Cf Ogni medaglio ha il suo reverso" says 
the well-known Italian proverb. So it is 
with the vexed question under consideration. 
I therefore proceed to an analytical examina- 
tion of the conclusions which men of great 



222 On the Sanatory and 

experience, of undoubted eminence and 
veracity have arrived at in favour of an 
opposite hypothesis. 

In the foremost rank among those who 
advocate the lunar theory, the illustrious 
Frenchman, Pinel, justly occupies a 
proud, elevated, and conspicuous position. 
The scientific world bows with profound 
respect and reverence to every opinion to 
which his masterly intellect gives expression. 
This eminent physician thus addresses him- 
self to the subject : cc It is curious to trace 
the effects of sol-lunar influence upon the 
return and progress of maniacal paroxysms. 
They generally begin immediately after the 
summer solstice, are continued with more 
or less violence during the heat of summer, 
and commonly terminate towards the de- 
cline of autumn. This duration is limited 



Physiological Influence of Light. 223 

within the space of three, four, or five months, 
according to deficiency of individual sen- 
sibility, and according as the season may 
happen to be earlier, later, or unsettled as 
to its temperature. Maniacs of all descrip- 
tions are subject to a kind of effervescence 
or tumultuous agitation upon the approach of 
stormy or very warm weather. They then 
walk with a firm but precipitate step ; they 
declaim without order or connexion ; their 
anger is roused by trivial or imaginary 
causes, and they express their feelings by 
clamorous and intemperate vociferation.* 
We must not extend this law of solar 
influence beyond its natural boundary, nor 

* In the year 1807, Mr. Thornton, then one of the 
apothecaries of Bethlehem Hospital, paid particular attention 
to the influence of the morning light upon all the patients 
that were at the time confined in the asylum. He came to the 
conclusion that many of them became noisy as soon as the 



224 On the Sanatory and 

conclude that the return of maniacal parox- 
ysms is invariably dependent upon the at- 
mosphere. I have seen cases in which the 
paroxysms return upon the approach of 
winter, i.e., when the cold weather of De- 
cember and January set in ; and this re- 
mission and exacerbation corresponded with 
changes of the temperature of the atmo- 
sphere from mildness to severe cold." 

The preceding quotation from PinePs 
treatise on insanity is entitled to profound 
respect. His sphere of observation was 
great, his experience large, his veracity 
unimpeachable, and what he saw he truth- 
fully recorded. I think, therefore, we are 

day began to break, and that, with the exception of two 
or three recent cases, they all became silent and quiet 
after night. During the eclipse of the sun on the 16th 
of June, 1806, there was a sudden and total silence in 
all the cells of the hospital! 



Physiological Influence of Light. 225 

bounds even in opposition to our own 
judgment^ to bow with great deference to 
the conclusion at which this distinguished 
physician arrived with regard to the in- 
fluence of the moon on the insane. 

Daquin, another eminent physician, 
directed his attention to this subject. 
He occupied a high professional position 
in France, and was universally respected 
for the zeal with which he cultivated 
science, and the faithful accuracy displayed 
in recording the results of his experience. 
He was a close observer of nature, a man 
of truth, and of highly, cultivated under- 
standing. 

In 1 79 1 he published an able work on 
insanity. In this he enters at length into 
a discussion of this vexed question. With- 
out quoting in detail the remarks of 



226 On the Sanatory and 

Daquin, I shall content myself with gene- 
ralizing the data brought forward in sup- 
port of the opinion he has formed with 
reference to the influence of the moon 
upon the mind when in a state of aber- 
ration. He says : — 

cc It is a well-established fact that in- 
sanity is a disease of the mind upon which 
the moon exercises an unquestionable in- 
fluence. The new moons and the last 
quarters of the moon are the lunar phases 
which influence the insane most frequently 
and painfully. 

" The first quarters and the full moons 
are the phases which I have observed to 
have the least influence in inducing relapses 
of insanity ; the insane at these periods being 
less insane and quieter, and they reasoned 
almost as if they were not ill at all. 



Physiological Influence of Light. 227 

cc Those who are still susceptible of being 
cured, as well as those who have been 
cured, are precisely those upon whom the 
two most powerful lunar phases have had 
the greatest influence during the whole 
of their illness. 

cc Those who are acutely maniacal are 
much more susceptible to the influence of 
the lunar phases than others. 

cc I have also observed a difference be- 
tween the influence exerted by this planet 
on madness characterized by excessive joy, 
and that by sorrow and melancholy. 

" It is proved that this influence is much 
more marked in parts of the countries 
bordering on the sea than in those at 
a distance from it."* 

Amidst this conflict of testimony, what 

* Daquin, " Philosophic de la Folie," 1st edition, 179 1. 
Q_3 



228 On the Sanatory and 

conclusions can legitimately be drawn ? Are 
we to consider the theory of lunar in- 
fluence as a myth and an idle fable, or as a 
well-established fact based upon accurate 
and scientific data ? It is impossible alto- 
gether to ignore the evidence of such men 
as Pinel, Daquin, Guislain, and others, and 
yet the experience of modern psychological 
physicians is to a great degree opposed to 
the deductions of these eminent men.* Is 

* Guislain has recorded the history of an insane patient 
on whom the influence of the moon was observed. He 
became maniacal every twenty-eight days. This dis- 
tinguished physician says, u We have among our female 
patients a maniac sixty years of age. Her attacks of 
acute insanity are periodical ; the return of the disease 
corresponding with the return of the full moon" — \Leqom 
Orales sur les Phr tenopathies, Gand, 1852.] 

In a work entitled, " De l'Electricite du Corps Humain," 
by Mons. TAbbe Bertholon, the case of a lunatic is 
recorded whose periodical accessions of acute mania oc- 
curred invariably at the full of the moon. 



Physiological Influence of Light. 229 

it not probable that there is some degree 
of truth on both sides of the question ; in 
other words, that the alleged changes ob- 
served among the insane at certain phases 
of the moon may .arise, not from the direct, 
but the indirect influence of this planet ? 
It is well known that certain important and 
easily recognisable meteorological pheno- 
mena result from the varied positions of 
the moon ; that the rarity of the air, the 
electric conditions of the atmosphere, its 
degree of heat, dryness, moisture, and 
amount of wind prevailing, are all, more 
or less, modified by the state of the 
moon. In the generality of bodily diseases 
what obvious changes are observed to 
accompany the meteorological conditions 
referred to ? Surely those suffering from 
diseases of the brain and nervous system 



230 On the Sanatory and 

affecting the mind cannot, with any show 
of reason, be considered as exempt from the 
operation of agencies that are universally- 
admitted to seriously affect patients afflicted 
with other maladies ? That the insane do 
appear to a degree unusually agitated at the 
full of the moon, particularly if its bright 
light is permitted uninterruptedly to enter 
the room where they sleep, there cannot be 
a doubt.* This phenomenon may, I think, 
be accounted for apart altogether from the 
hypothesis of there being anything specific 
in the composition of the lunar ray. 

In certain forms of insanity, particularly 
those characterized by illusions of the 

* An intelligent lady, who occupied for about five years 
the position of matron in my establishment for insane 
ladies, has remarked, that she invariably observed a great 
agitation among the patients when the moon was at its 
full. This must be accepted quantum <valeat. 



Physiological Influence of Light. 23 1 

senses or hallucinations of the mind, how 
materially affected the patients are by the 
kind and degree of light admitted into their 
chambers. If exposed to a great degree 
of natural, or even artificial light, the hallu- 
cinations often become painfully intensified. 
Sleeplessness often thus arises, and dormant 
morbid visual and aural conditions pre- 
viously in a latent state, become actively de- 
veloped. Patients afflicted with distressing 
delusions often imagine that everything they 
see hasassumed the form of aterrible spectral 
image. The presence of light emanating 
from the moon, when at its full greatly tends 
in these cases to aggravate the lunatic's mental 
sufferings. It is occasionally most desirable 
to exclude light altogether from bedrooms 
occupied by the insane, in order to tranquil- 
lize them and cause sleep. In other instances 



232 On the Sanatory and 

the patient's condition of mental excitement 
becomes aggravated by being kept for a 
length of time in darkness. It is therefore 
often necessary, with the view of dissipating 
a false creation which has seized hold of 
his disordered imagination, to admit light 
freely into the chamber. This has been 
known immediately to compose the patient, 
by convincing him of the morbid and illu- 
sory character of his mental impression, and 
inducing him to exclaim, — 

" There is no such thing ! 
Il: is [my disordered brain]* which informs 
Thus to mine eyes."f 

* I hope I shall not expose myself to critical censure 
for substituting the words " disordered brain" for " bloody 
business." 

-j- Shakspeare has with exquisite poetic beauty and 
wonderful psychological truth delineated, in the passage 
from which the preceding lines are taken, the sudden 
transition of the mind from apparent insanity (assuming 
the form of an illusion of the senses) to that of health. 



Physiological Influence of Light. 233 

If I were to confine the concluding re- 
marks to the result of my own observations 
on this subject, I fear I should be able to 
add but little to what others have written 
in relation to it. I freely admit that, placing 
but little faith in what has been recorded or 
said on the subject, I have not kept any 
systematic register as to the effect of dif- 
ferent phases of the moon on the insane. 

It has been observed by Some officials 
connected with lunatic asylums, that occa- 
sionally, from causes unknown to them, 
many of the patients have simultaneously 
exhibited a state of unnatural agitation. 
This condition of the inmates has occurred 
several times during the year, and at 
irregular intervals ; but the state of the 
moon at the time was not made a matter of 
observation. It is difficult to assign any 



234 On the Sanatory and 

cause for the alleged phenomenon, and it 
would not be entitled to a moment's con- 
sideration if the commotion and excitement 
that are said to take place were confined to a 
few of the patients; but as many of the 
insane inmates (several of them occupying 
separate rooms) were noticed to be thus 
affected, at the same day and hour, the fact 
becomes one worthy of record.* 

* There can be no doubt that bright red, and yellow 
rays stimulate and in some cases irritate the brain and 
mind. Deep blue is said to depress or exhaust the vital 
force. Some animals are excited when brought in contact 
with scarlet colour. This is observed at the bull-fights 
that take place in different parts of Spain. Green, 'violet, 
and in fact all the neutral tints, soothe the nervous system 
and allay mental irritation. Those who have the care of 
the insane, or medical treatment of patients suffering from 
great brain irritability, should bear these facts in remem- 
brance. 



Physiological Influence of Light. 235 



PART IV. 



HYGIENE OF LIGHT. 



Having in the introductory part of this 
work; referred in general terms to the 
sanatory influence of light, I return to the 
subject in order to point out more specifically 
the deleterious effect of its absence on the 
bodily health. I have previously alluded 
to the important changes that take place in 
the constitution of the blood in consequence 
of the cutaneous vessels on the surface of 
the body not being freely exposed to the 
oxygenating and life-generating influence of 
the sun. 

It is a well-established fact that, as the 



235 On the Sanatory and 

effect of isolation from the stimulus of light, 
the fibrine, albumen, and red blood- cells 
become diminished in quantity, and the 
serum, or watery portion of the vital fluid, 
augmented in volume, thus inducing a 
disease known to physicians and patho- 
logists by the name of leukemia, an affection 
in which white instead of red blood-cells are 
developed.* This exclusion from the sun 
produces the sickly, flabby, pale, anasmic 
condition of the face, or exsanguined ghost- 
like forms so often seen among those not 
freely exposed to air and light. The 
absence of these essential elements of health 
deteriorates by materially altering the phy- 
sical composition of the blood, thus seriously 
prostrating the vital strength, enfeebling 

* Virchow's " Cellular Pathology/' i860. 



Physiological Influence of Light. 23 7 

the nervous energy, and ultimately inducing 
organic changes in the structure of the 
heart, brain, and muscular tissue.* Do not 
these facts suggest the great importance, 
particularly in a northern climate like that 
of England, where the bright beams of the 
sun so seldom shine, of so constructing our 
habitations, both with regard to the number 
of windows and position of the buildings, as 

* "Where light is not permitted to enter the physician 
will have to go," is the translation of a well-known Italian 
proverb. In the eloquent words of Sir David Brewster, 
" Light is the very life-blood of nature, without which 
everything material would fade and perish ; the fountain of 
all our knowledge of the external universe ; and the his- 
toriographer of the visible creation, recording and trans- 
mitting to future ages all that is beautiful and sublime in 
organic and inorganic nature, and stamping on perennial 
tablets the hallowed scenes of domestic life, the ever-varying 
phases of social intercourse and the more exciting scenes of 
bloodshed and war, which Christians still struggle to 
reconcile with the obligations of their faith." 



238 On the Sanatory and 

to admit within their walls a sufficient 
degree of air and light ; and are we not 
bound to impress upon the legislature the 
necessity of enacting some stringent pro- 
tecting measures, with the view of pre- 
venting low damp cellars and rooms being 
crowded together, into which air and light 
vainly struggle to penetrate, and where 
so many thousands of the poorer classes 
in our large towns are compelled to dwell, 
to the utter sacrifice of every comfort 
worth living for, and positive ruin to the 
health of both body and mind ?* In several 

* The following is an extract from a recently published 
report of the health commissioners of the State of New 
York : — " In no other city in the civilized world is there to 
be found half a million of people so unhealthily housed, as a 
class, as the tenant house population of New York. In less 
than sixteen thousand houses, on lots that average scarcely 
twenty- five by one hundred feet, there dwell nearly five 
hundred thousand people; and in the cellars of those 



Physiological Influence of Light, 239 

English manufacturing cities, until within 
the last few years, the great proportion 

houses nearly sixteen thousand more poor, whose poverty 
and ignorance allow no election of better homes." 

The Rev. Isaac Taylor, incumbent of St. Matthias, 
Bethnal Green, thus describes in a printed circular the 
terrible state of the poor of his parish. The statement 
is copied from the Pall Mall Gazette of February 12. 
ft The mortality among young children is something flight • 
ful. I do not know anything more terrible than the state- 
ments which one continually hears. It is a common thing 
for a mother to say that she has buried six or eight, and 
reared one or two. This mortality among the children is 
chiefly owing to the deadly overcrowding, and to insuffi- 
ciency of food and clothing. Last summer we found a 
family of eight children living with their father and mother 
in a room some ten feet square, and almost in a state of 
starvation. All the children had the small-pox out upon 
them ; they had no medical care or nursing ; the only 
medicament that had been used was a little oil rubbed 
over their faces ; this the father said he had heard was 
good for the small-pox. The man was engaged meanwhile 
in the delicate work of making white chenille, to be sold 
in the fashionable West-end shops. Hardly a family in 
the parish possesses more than a single room, in which all 
the members live, work and sleep." 



240 On the Sanatory and 



of the working classes lived either under- 
ground, in courts, or in narrow streets, and 
houses almost destitute of windows, ap- 
parently constructed for the specific purpose 
of admitting the minimum portion of air 
and the smallest possible degree of light 
consistent with the preservation of health 
and the maintenance of life.* It was com- 
puted not many years ago that in Liverpool 

* Sir David Brewster, in his opening address delivered in 
November of last year at the Royal Society of Edinburgh, has 
suggested an easy and valuable remedy for these frightful 
evils. His remarks afford a valuable illustration of the 
facility with which the great truths of science may be 
practically applied in promoting the comfort and health of 
the human race : — " If, in a very narrow street or lane, we 
look out of a window with the eye in the same plane as 
the outer face of the wall in which the window is placed, 
we shall see the whole of the sky by which the apartment 
can be illuminated. I f we now withdraw the eye inwards, 
we shall gradually lose sight of the sky till it wholly dis- 
appears, which may take place when the eye is only 6 in. or 
8 in. from its first position. In such a case the apartment 



Physiological Influence of Light, 241 

between 30,000 and 40,000 people lived in 
cellars. As a consequence of this state of 
things, the health of the working classes 
became seriously affected. Legislative 
measures were adopted for the purpose of 
declaring such habitations illegal, and those 
living in them were ejected by the strong 
arm of the law. In 1849, 4,7 00 cellars 
were cleared of 20,000 inhabitants. 

is illuminated only by the light reflected from the opposite 
wall, or the sides of the stones which form the window ; 
because, if the glass of the window is 6 in. or 8 in. within 
the wall, as it generally is, not a ray of light can fall upon 
it. If we now remove our window, and substitute another 
in which all the panes of glass are roughly ground on the 
outside, and flush with the outer wall, the light from the 
whole of the visible sky, and from the remotest part of the 
opposite wall, will be introduced into the apartment, re- 
flected from the innumerable faces or facets which the 
rough grinding of the glass has produced. The whole 
window will appear as if the sky were beyond it, and from 
every point of this luminous surface light will radiate into 
all parts of the room." 

R 



242 On the Sanatory and 

Rightly recognising the life-giving and 
health-sustaining influence of light, the 
cc Towns Improvement Clauses Act of 
Scotland " enacted that no cellars less than 
seven feet high, without a window, and of 
which more than two-thirds are below the 
level of the street, should be inhabited. 
Acting upon the authority of this statute, 
the corporation of the city of Edinburgh 
has considerably improved the physical con- 
dition of the working classes of that town 
by peremptorily closing 3,000 dreary, sun- 
less dens, in which the poor people were in 
the habit of residing. 

How eloquently and truthfully has Sir 
David Brewster illustrated this section of 
my subject. He says : — cc If the light of 
day contributes to the development of the 
human form, and lends its aid to art and 



Physiological Influence of Light. 243 



nature in the cure of disease, it becomes 
a personal and national duty to construct 
our dwelling-houses, schools, workshops, 
factories, churches, villages, towns, and 
cities upon such principles and in such 
styles of architecture as will allow the 
life-giving element to have the fullest and 
the freest entrance, and to chase from every 
crypt, cell, and corner the elements of 
uncleanness and corruption which have a 
vested interest in darkness. 

cc Although I have not visited the prisons 
and lazarettos of foreign countries, to de- 
scribe the dungeons and caverns in which 
the victims of despotism and crime are 
perishing without light and air, yet we have 
seen enough in our own country — in private 
houses, in the most magnificent of our 
castles, and in the most gorgeous of our 
R % 



244 On the Sanatory and 

palaces — to establish the fact that there is 
hardly a house in town or country without 
dark apartments which it is in the power of 
science to illuminate. In most of the 
principal cities of Europe, and in many of 
the finest towns of Italy, where external 
nature wears her brightest attire, there are 
streets and lanes in which the houses on one 
side are so near those on the other, that 
hundreds of thousands of human beings 
are neither supplied with light nor air, and 
carry on their trades in almost total dark- 
ness. Providence — more beneficent than 
man— has provided the means of lighting 
up to a certain extent the workman's home, 
by the expanding power of the pupil of his 
eye, and by an increasing sensibility of his 
retina ; but the very exercise of such 
powers is painful, and every attempt to see 



Physiological Influence of Light, 245 

when seeing is an effort, or to read and 
work with a straining eye and an erring 
hand, is injurious to the organ of vision, 
and sooner or later must impair its powers. 
Thus, deprived of the light of day, thou- 
sands are compelled to carry on their trades 
principally by artificial light — by the con- 
sumption of tallow, oil, or gas — thus in- 
haling from morning till midnight the 
offensive odours and polluted effluvia which 
are more or less the products of artificial 
illumination. 

"It is in vain to expect that such evils, 
shortening and rendering miserable the life 
of man, can be removed by legislation or 
arbitrary power. In various great cities 
attempts are making to replace their densely 
congregated streets and dwellings by struc- 
tures at once ornamental and salutary ; and 



246 On the Sanatory and 

Europe is now admiring that great renova- 
tion in a neighbouring metropolis, by which 
hundreds of streets and thousands of 
dwellings, once the seat of poverty and 
crime, are replaced by architectural com- 
binations the most beautiful, and by hotels 
and palaces which vie with the finest edifices 
of Greek or of Roman art."* 

Fourcault cites a striking illustration of 
the sad effects of the absence of light on the 
health of young children. On one occasion 
his attention was attracted to the mutilated 
condition of several large mulberry trees, 
the branches of which, before their decay, 
effectually shaded the schoolroom in which 
a number of orphan girls affected with 
chronic diseases were educated. On asking 



* " An Address delivered at the Opening of the Session 
for 1866-7, at the Royal Society, Edinburgh." 



Physiological Influence of Light. 247 

the reason for the mutilation, he was in- 
formed that the shade of the trees visibly- 
increased the severity of the scorbutic affec- 
tions that prevailed among the children, 
and that a very favourable change had taken 
place in the condition of the girls since their 
exposure to the unimpeded light of the sun.* 
Utterly regardless of the principles just 
enunciated, how often do we see parents, 
who cannot for a moment be considered in- 
different as to the present and future health 
of their offspring, adopting the most in- 
genious means of effectually excluding light 
from the bodies of young infants and 
children ! No course can be more detri- 
mental to their health than the one just 
referred to, because the value of an im- 

* a Causes Generates des Maladies Chroniques/' p. 42. 



248 On the Sanatory and 

portant vital element is systematically ignored 
at a period of life when it is of the highest 
importance it should be brought to bear upon 
the purification of the blood, and consequent 
healthy development of organic structures. 

Children, even at an early age, should 
not be excluded, particularly during the 
warm periods of the year, from the genial 
and cheering influence of the sun. The 
sanatory effect of light can be easily 
made available even during the winter 
months (in rooms properly ventilated and 
heated) with little or no danger. Great 
benefit to the health would accrue by giving 
children what the ancients termed solaria, 
or <c solar-air baths ;" that is, permitting 
them to lie naked upon the bed or floon 
free from the incumbrance of swaddling- 
clothes, so that their bodies may be 



Physiological Influence of Light. 249 

thoroughly brought under the influence, 
for some period of the day, of good air and 
bright sunlight. The children of savages, 
as well as of negroes, who are often allowed, 
as soon as they can walk alone to run about 
in the open air (in puris naturalibus) freely 
exposed to the influence of light, have 
finely-developed muscular structures, and 
generally enjoy robust health.* 



* " Passing round St. Paul's Churchyard the other day, 
our ear caught a low confused sound, which seemed to 
issue from behind a grille under the gloomy portico of St. 
Paul's School. Attracted by so unusual a sound, and 
blinded for a moment by passing from the sunlight under 
the portico, we at length made out that the sound was 
that of boys' voices in play. After a little time, when our 
eyes had become accustomed to the darkness, and permitted 
us to penetrate the dreary recess, we perceived that some 
score of boys were actually at play within its unhappy 
shade. Such a profound sanatory error on the part of the 
authorities of the school as to shut up. their youth in a 
cage, without light or air, and there bid them play, struck 



250 On the Sanatory and 

No amount of artificial, polarized, or 
reflected light will compensate for the 
want of the direct action of the sun. 

Humboldt, in the account he has pub- 
lished of his voyage to the equinoctial re- 
gions, says, when speaking of the Chaymas, 



us with some astonishment. Boys at their games are like 
young birds singing on the bough; half their joy is a 
result of the influence of the sunny air. We are told, 
indeed, that only a very short time is spent in this gloomy 
retreat ; but surely it is hard that the hour of recreation, 
when academic art should give way to nature, should be 
selected for this depressing process as at present carried 
on. What would Dean Colet have said to it ? When 
the St. Martin's national school, leading out of Endell- 
street, was built some years ago, we noticed with plea- 
sure that a playground was built at the top of the school, 
where light and air were plentiful, conditions essential in 
a playground where children use violent exercise ; but 
this example we are sorry to see has no effect upon 
the Mercers' Company. The necessity of light for 
young children is not half appreciated. Many of the 
afflictions of children, and nearly all the cadaverous looks 



Physiological Influence of Light. 251 

cc both men and women (whose bodies are 
constantly inured to the effect of light) are 
very muscular, and possess fleshy and 
rounded forms. It is needless to add that 
I have not seen among these people a 
single case of natural deformity. I can say 

of those brought up in great cities, are ascribable to 
this deficiency of light and air. When we see the glass- 
rooms of the photographers in every street high up on 
the topmost story, we grudge them their application to a 
mere personal vanity. Why should not our nurseries be 
constructed in the same manner ? If mothers knew the 
value of light to the skin in childhood, especially to 
children of a scrofulous tendency, we should have plenty 
of these glass-house nurseries, where children may run 
about in a proper temperature, free of much of that 
clothing which at present seals up the skin — that great 
supplementary lung — to sunlight and oxygen. Glass- 
house nurseries lifted up to the topmost story would save 
many a weakly child that now perishes for want of those 
necessaries of infant life." 

I copy the preceding sensible remarks, so strictly in 
conformity with my own views, from the Pall Mall 
Gazette. They are from the pen of Dr. Andrew Wynter. 



25 2 On the Sanatory and 

the same of many thousands of Caribs, 
Maysias, Mexicans, and Peruvian Indians, 
whom I observed during five years. De- 
formities and deviations from healthy phy- 
sical development are exceedingly rare in 
certain races of men, especially those which 
have the skin strongly coloured, who 
wander about naked under the brilliant 
light of the tropical regions. These have 
muscular fleshy bodies, rounded contours, 
and present none of those deformities so 
frequently observed among the inhabitants 
of other climates." 

Dr. Bryson, in his memorandum to the 
Lords Commissioners of the Admiralty re- 
lating to the health of seamen, has pointed 
out the great difference between the ap- 
pearance of sailors employed in the dark 
bread-room and holds of ships, and those 



Physiological Influence of Light. 253 

who are freely exposed to air and sunlight 
on deck, or in open boats, at all hours of 
the day : he therefore considers it of im- 
portance to "ascertain whether exclusion 
from the solar rays be not, to a greater 
extent than is generally believed, one reason 
why these men, who have in consequence 
acquired a pale waxy look from confine- 
ment below, are more susceptible to disease, 
and less capable of sustaining its shocks, 
than are those whose blood is enriched and 
strengthened by the free exposure to light, 
heat, and air which their different avoca- 
tions ensure. The force of these remarks, 
however, will be best understood by those 
who have had opportunities of witnessing 
the rapid change which takes place in the 
human constitution by exposure for only 
a short time to the direct rays of a tropical 



^54 O n the Sanatory and 

sun. Why, in a state of perfect repose, 
the blood should acquire a brighter tinge 
and an increased force of circulation are 
inquiries the value of which the observant 
physiologist will not fail justly to appreciate; 
neither will he fail, as often as opportunities 
occur, to follow up these phenomena, should 
they terminate in disease, or unhappily 
produce death."* 

The inestimable value of light as an 
element in the preservation of health 
and treatment of disease, should be fully 
appreciated in the construction of all streets 
and buildings, particularly those intended 
as habitations for the poor, or public 
hospitals for the treatment of disease. It 



* u Manual of Scientific Inquiry," published by autho- 
rity of the Lords Commissioners of the Admiralty, edited 
by Sir John F. W. Herschel, Bart. London, 1849. 



Physiological Influence of Light, 255 

is a well-ascertained fact that many mala- 
dies are more susceptible of amelioration, if 
not of cure, provided the light of the sun 
is freely admitted into the rooms or wards 
where invalids are domiciled.* 

Apart altogether from the cheerfulness 
and mental serenity (important auxiliaries in 
the eradication of disease !) which the bright 
rays of the sun invariably engender, light 
has a thermic influence upon the mind and 

* Some years ago, when visiting the great hospital of 
St. John, at Brussels, I was much impressed with the 
most judicious hygienic arrangements made in the con- 
struction of that building for the health and comfort of 
the invalids. On the roof of the hospital an elegant 
garden is laid out with great taste, and planted with 
shrubs, small trees, and a grass lawn, interspersed with 
pretty and sweet-smelling flowers. It is, in fact, a Pare 
de Monceau in miniature. In this quiet rural retreat, 
patients, particularly the convalescents, are permitted at 
certain hours of the day to promenade, indulging in the 
luxury of good air and bright sunlight. 



256 On the Sanatory and 

body when prostrated by serious ailments, 
and certainly acts beneficially by chemically 
purifying the blood of the patient, as well 
as the atmosphere of the apartment he 
occupies. 

There are, of course, active conditions 
of bodily and mental disease, such as small- 
pox, inflammatory conditions of the skin 
and brain, acute mania, ophthalmia, &c, 
which require to be carefully excluded from 
the stimulus of light. I have elsewhere 
addressed myself to this subject. 

Florence Nightingale has entered so fully 
into this subject, that I offer no apology 
for quoting in extenso her extremely judi- 
cious remarks relative to the importance of 
keeping prominently in view, in the archi- 
tectural construction of public hospitals, the 
sanatory value of light to the sick. She says : 



Physiological Influence of Light, 2 S7 

c< Second only to fresh air, however, I 
should be inclined to rank light in im- 
portance for the sick. Direct sunlight, not 
only daylight, is necessary for speedy reco- 
very; except, perhaps, in certain ophthalmic 
and a small number of other cases. In- 
stances could be given, almost endless, 
where, in dark wards or in wards with a 
northern aspect, even when thoroughly 
warmed, or in wards with borrowed light, 
even when thoroughly ventilated, the sick 
could not by any means be made speedily 
to recover. 

cc Among kindred effects of light I 
may mention, from experience, as quite 
perceptible in promoting recovery, the 
being able to see out of a window, in- 
stead of looking against a dead wall ; the 
bright colours of flowers ; the being able 



258 On the Sanatory and 

to read in bed by the light of a window 
close to the bed-head. It is generally said 
that the effect is upon the mind. Perhaps 
so ; but it is no less so upon the body on 
that account. 

cc All hospital buildings in this climate 
should be erected so that as great a surface 
as possible should receive direct sunlight — 
a rule which has been observed in several 
of our best hospitals, but, I am sorry to say, 
passed over in some of those most recently 
constructed. Window-blinds can always 
moderate the light of a light ward ; but the 
gloom of a dark ward is irremediable. 

cc The axis of a ward should be, as nearly 
as possible, north and south ; the windows 
on both sides, so that the sun shall shine 
in (from the time he rises till the time 
he sets) at one side or the other. There 



Physiological Influence of Light. 259 

should be a window to at least every two 
beds, as is the case now in our best hospi- 
tals. Some foreign hospitals, in countries 
where the light is far more intense than in 
England, give one window to every bed. 
The window-space should be one-third of 
the wall-space. The windows should reach 
from two or three feet of the floor to one 
foot of the ceiling. The escape of heat 
may be diminished by plate or double glass. 
But while we can generate warmth, we can- 
not generate daylight, or the purifying and 
curative effect of the sun's rays."* 

Many facts are on record, illustrative of 
the decidedly beneficial effect of the free 
admission of light into public buildings set 
apart as receptacles for cases of disease. 

* a Notes on Hospitals," by Florence Nightingale. 
Third edition, pp. 19, 20. London: Longmans, 1863. ' 

S 2 



26o On the Sanatory and 

Sir James Wylie, of the Imperial Russian 
Service, pointed out to an English physi- 
cian one of the barracks at St. Petersburg, 
in which three cases of disease occurred on 
the dark or shaded side of the establish- 
ment for one on the other, though the 
apartments on both of these sides com- 
municated freely with each other, and the 
discipline, diet, and treatment were in every 
respect the same.* 

A very remarkable instance of recovery 
from disease has been related by the late 
Baron Dupuytren, the eminent French sur- 
geon, and cited in a work on Light published 
by the Society for Promoting Christian 
Knowledge. A lady residing in Paris, had 
suffered for many years from an enormous 

* " On the Theory and Practice of Ventilation," by 
R. B. Reid, M.D. 1855. 



Physiological Influence of Light. 261 

complication of diseases, which had baffled 
the skill of all her medical advisers, and 
her state appeared almost hopeless. As a 
last resource, the opinion of Dupuytren 
was requested upon her case, and he, un- 
able to offer any direct medical treatment, 
essentially differing from all that had been 
previously tried in vain, suggested that she 
should be taken out of the dark room in 
which she lived, and away from the dismal 
street, to a brighter part of the city, and 
that she should expose herself as much as 
possible to the daylight. The result was 
quickly manifest in her rapid improvement, 
and this continued until her recovery was 
complete. An equally singular instance 
has been related by Southey, in the case 
of his own parent.* 

* " In chlorosis, scrofula, phthisis, and, in general, every 



262 On the Sanatory and 

tc In the years of cholera, when this 
frightful disease nearly decimated the popu- 
lation of some of the principal cities in the 
world, it was invariably found that the 
deaths were more numerous in narrow 
streets and northern exposures, where the 
salutary beams of light and actinism had 



disease characterized by deficiency of vital power, light 
should not be debarred to the patient. In convalescence 
from almost all diseases it acts, unless too intense or too 
long continued, as a most healthful stimulant, both to 
the nervous and physical systems. The evil effects of 
keeping such invalids in obscurity are frequently very de- 
cidedly shown, and cannot be too carefully guarded against 
by the physician. The delirium and weakness, which are 
by no means seldom met with in convalescents kept in 
darkness, disappear like magic when the rays of the sun 
are allowed to enter the chamber. I think I have no- 
ticed that wounds heal with greater rapidity when the 
light is allowed to reach them than when they are kept 
continually covered." (Dr. Hammond's "Treatise on 
Hygiene.") 



Physiological Influence of Light. 263 

seldom shed their beneficial influence. This 
resistless epidemic found an easy prey among 
a people whose physical organization had 
not been matured under those benign in- 
fluences of solar radiation which shed health 
and happiness over our feftle plains, our 
open valleys, and those mountain sides 
and elevated plateaus where man breathes 
in the brighter regions of the atmosphere."* 
I have spoken previously of the inesti- 
mable benefits which accompany a liberal 
exposure of the body to the action of the 
solar beam. I cannot pass unnoticed the 
positive mischief that often arises from a 
prolonged action of intense light on the 
visual organs, as well as the injury often 
caused by a sudden transition from a 



* Sir D. Brewster. 



264 On the Sanatory and 

moderate to a great or glaring degree of 
the sun's influence.* 

Soldiers are said often to suffer in their 
eyes from the reflection of the rays of the 
sun from white sand or snow. Levy records 
that in 1819 trre Swiss troops in garrison at 
Lyons had many of their number affected 

* A sudden transition from perfect darkness (particularly 
if of considerable duration) to an intense degree of light 
produces a most painful and dazzling sensation in the 
retina, accompanied by a feeling of acute pain in the eye- 
balls, as well as of the head. These symptoms are often 
associated with temporary blindness. The tyrant Dionysius, 
being aware of these facts, inflicted on some of his unhappy 
prisoners the severe punishment of compelling them to pass 
rapidly from great darkness to the full blaze of the sun in 
recently white- washed rooms ! 

An officer of high rank in the army of Charles I. went 
to Madrid, with the view of executing an important mission 
for the king, but failing in his generous attempt to do his 
Majesty a signal service, he was arrested by the Spanish 
Government, and ordered to be incarcerated in a dark and 
dismal dungeon, into which light never entered except 
when a small hole at the top of the cell was opened 



Physiological Influence of Light. 265 

with hemeralopia, accompanied with ner- 
vous symptoms, such as nausea and vomit- 
ing, caused, it is supposed, by drilling under 
a hot sun.* 

This disorder of the vision is said to 
arise from two very different causes : 1st, 
an exposure to a stronger light than the eye 
has been accustomed to ; 2ndly, a deficiency 
of the black pigment which lines the choroid 
membrane. This affection of the eye is 
commonly observed among those who live 

by the jailer for the purpose of giving the prisoner 
food. This unfortunate Royalist was confined in the 
dungeon for several months : he was then set at liberty. 
Such, however, was the effect of the darkness upon his 
nervous system, eyes, and optic nerve, that he was 
compelled to live for some time afterwards in a dark 
room, in order gradually to accustom himself to the 
stimulus of light. 

* A form of intermittent blindness, characterized by 
the patient being able to see only in broad daylight, and 
becoming totally blind at sunset. 



266 On the Sanatory and 

in dark caverns, mines, dungeons, or prisons. 
It is frequently seen among the peasants of 
Italy, who are employed in agricultural pur- 
suits. This is attributed to the peculiar 
brightness of the Italian sky, remark- 
able clearness of the atmosphere, and re- 
laxingly warm condition of its tempera- 
ture. The peasants of Italy are thus ex- 
posed to the joint operation of almost every 
cause that can produce habitual debility of 
the iris and irritability of the retina. This 
complaint is most frequent on return of 
spring, or at the vernal equinox. 

Ramazzini says that such is the degree of 
dimness of vision which this exposure to 
intense light induces, that the peasants lose 
their way in the fields in the glare of noon, 
but that on the approach of night they are 
again able to see distinctly. In the treat- 



Physiological Influence of Light. 267 

ment of these cases it is found necessary to 
keep the patients for some weeks in the 
shade, or in comparative darkness, until the 
eyes recover their healthy tone. This disease 
of the eye is said to be endemic in some 
parts of France, particularly in the neigh- 
bourhood of Roche Guion, on the banks of 
the Seine. So generally does it prevail 
that we are told upon good authority, that 
it affects one in twenty of the inhabitants in 
one village, and in another, one in ten every 
year. It shows itself in the spring, and 
continues for three months, returning in a 
slighter degree in the autumn. The soil of 
this part of France consists of dazzling 
chalk, and it is thought that the intensity of 
the first reflected light after the dreariness of 
the winter in all probability is the cause of 
the malady. 



268 On the Sanatory and 

This is a common affection in Russia 
during the summer months, when the eyes 
are exposed almost without intermission to 
the constant action of light, as the sun then 
dips but little below the horizon, and there 
is scarcely any interval of darkness. The 
peasants who protract their hard labour in 
the fields from a very early to a very late 
hour, and at the same time exhaust and 
weaken themselves by their daily fatigue, 
are subject to this malady. Mr. Guthrie 
has published an account of a detachment 
of Russian soldiers, in which this disorder 
suddenly manifested itself. They were 
ordered to attack a Swedish post at the 
moment the affection of the eyes developed 
itself, and had nearly destroyed one another 
by mistake, owing to their visual powers 
being impaired. These soldiers had been 



Physiological Influence of Light. 269 

harassed by long marches, and exposed 
night and day to the piercing glare of 
an uninterrupted range of snowy moun- 
tains.* 

cc The only persons I have myself seen 
affected with hemeralopia have been those 
just returned from sea voyages — most com- 
monly from the East or West Indies — and 
who have consequently been exposed to a 
strong glare of sunlight. The affection is, 
I believe, also met with among the inhabi- 
tants of the inland parts of India, who 
attribute it, just as our own sailors do, 
to sleeping when exposed to the moon- 
beams. 



* « Mem. de la Societe Royale de Med., 1786." " Me- 
moirs of the Medical Society of London," by Mr. Guthrie. 
" The Study of Medicine," by John Mason Good, M.D., 
F.R.S. 



270 On the Sanatory and 

cc The real cause of hemeralopia appears 
to be exhaustion of the nervous suscepti- 
bility of the retina from over-excitement by 
the sun's rays, whereby the part is rendered 
incapable of appreciating the milder rays of 
twilight or moonlight. 

cc But this exposure to strong light is not 
always the cause of the affection ; for I have 
met with it among those who had never 
quitted the temperate parts of the globe. 
In most of the latter cases, however, the 
complaint has shown itself after voyages 
which had subjected the patients to exhaust- 
ing labour, and exposure to severe weather, 
when deprived of their proper supply of 
fresh provisions and vegetables. 

cc I have commonly found that a few 
weeks' residence on shore, with a whole- 
some mixed diet and the use of quinine, 



Physiological Influence of Light. 271 

has restored their vision to a healthy 
state."* 

This disorder of the vision is generally 
associated with a scorbutic condition of the 
system. It prevailed to a considerable 
extent among the French and English 
soldiers during the Crimean campaign. It 
no doubt arose from their long-continued 
exposure to an intense glare of light, 
which their eyes had not been accustomed 
to. An eminent American ophthalmic prac- 
titioner, says, that a surgeon attached to the 
garrison of Strasbourg, in France, has pro- 
posed what he claims to be a speedy and effec- 
tual mode of curing this malady, f He con- 

* " A Guide to the Practical Study of Diseases of the 
Eye," by James Dixon, F.R.C.S. England, Surgeon to 
the Royal London Ophthalmic Hospital, Moorfields 
London, 1866. 

t Dr. Henry W. Williams. 



272 On the Sanatory and 

fines his patients in an entirely dark room for 
a considerable number of hours, not allowing 
light to enter even for an instant. The eyes 
thus being left in complete repose, recover 
their normal tone. Relapses, he asserts, 
are quite rare, provided the seclusion has 
been of sufficient duration. Soldiers suf- 
fering from this ailment are advised to be 
removed into the interior of the country 
from seaboard stations, particularly if ex- 
posed there to the glare from white sand. 

Snow and ice blindness is a common affec- 
tion among those who reside for a considerable 
time in the Alpine or Arctic regions.* 

Sheep are known to temporarily lose their 
sight if permitted to wander over mountains 



* Dr. Hammond knew a child who was rendered per- 
manently blind by looking intently at a bright object 
while she was having her photograph taken. 



Physiological Influence of Light. 273 

covered with snow ; but it returns a short 
time after the snow and ice are melted. 

The Greek soldiers, as related by 
Xenophon, suffered severely in their eyes 
from the reflection of the intense light 
of the sun as they crossed the mountains of 
Armenia. 

It is impossible, whilst considering this 
matter, to leave altogether unnoticed the 
hygienic treatment of the eyes, when mor- 
bidly affected by artificial light. 

Persons exposed for an undue length of 
time to the glare of brilliantly-lighted rooms 
often suffer from chronic ophthalmia and 
other affections of the organ of vision. 
Literary men, from the same cause, are 
liable to attacks of muscle volitantes and 
amaurosis. Tailors, sempstresses, shoe- 
makers, jewellers, watchmakers, and, in 



274 On the Sanatory and 

fact, all who work by artificial light, are 
subject to serious disorders of the eye. 
Under these circumstances they often be- 
come acutely sensitive to light.* Ac- 
cording to a distinguished oculist, light is 
injurious to the eyes in proportion as the 
red and yellow rays prevail. These produce 
cerebral and visual excitement, followed 
by debility of the retina.f He suggests 

* Mr, Ernest Hart says that when great sensitiveness to 
light exists tinted (plain) spectacles are indicated. He ob- 
serves— "The ordinary smoked glasses may be advan- 
tageously substituted in such cases by those tinted of a 
cobalt blue, which sufficiently exclude the irritating yellow 
and red rays, without cutting off too much light, or pro- 
ducing an unpleasant obscurity." — u On some of the Forms 
of Disease of the Eye," by Ernest Hart, Ophthalmic Sur- 
geon to St. Mary's Hospital, &c, p. 21. 1864. 

f It has been established by direct, experiment that the 
•violet ray of the solar spectrum is actually capable of ren- 
dering a needle magnetic which has never been touched by 
the loadstone or by an artificial magnet (Steinmetz). 



Physiological Influence of Light. 275 

as a remedy for the injurious effects of 
red and yellow colours that the light 
should be surrounded by a shade, tinted 
blue on its inner surface. The blue rays 
reflected from it will produce a tolerably 
pure and white light, by their union with 
the reddish-yellow rays of the flame. To 
effect the same purpose the lamp should be 
enveloped by a glass chimney, tinged inside 
with a very pale blue, or the light should be 
made to pass through a fluid of the same 
colour.* 

In an early part of this work I have re- 
ferred in general terms to the important 
results obtained by Fraunhofer, Kirchhoff, 
and Bunsen, with reference to the existence 
of metallic lines ( cc Fraunhofer's lines ") 



* " Practical Remarks on Near and Aged Sight," by 
W. "White Cooper, Esq., F.R.C.S. England. 1847. 

T 2 



2 "6 On the Sanatory and 

observed in the sunlight by means of the 
spectrum.* It has naturally been a matter 
of discussion with medical men engaged in 
sanatory investigations, whether the "vapour 
of iron," found to exist in conjunction with 

* u We can no longer consider light as merely consisting 
of infinitesimal particles, or as infinitesimal waves ; we 
may now conclude that it is metallic, — that sunshine con- 
sists of a metallic i shower,' such as the Greek mythology 
ascribed to Jupiter in one of his unions with mortals 
(strange coincidence of fact with emblematic fiction !) ; 
but, instead of a shower of gold, according to the figment, 
the beneficent sunshine bathes us with elementary iron, 
sodium, magnesium, calcium, chromium, nickel, barium, 
copper, zinc, and hydrogen ! It is Jupiter, not Apollo, 
that the ancient mythology should have identified with the 
sun. In the idea of Zeus (or the l Burner') and the Zeuspater 
(Father Jove) of the Latins, we might translate all the 
amours of the Father of the Gods into physical facts con- 
nected with the <arch-chemic sun,' as Dante calls him, 
and recognise the idea that all animals are children of the 
sun." — " Sunshine and Showers," by Andrew Steinmetz, 
Esq., of the Middle Temple, Barrister- at- Law. London, 
1867. 



Physiological Influence of Light, 277 

other metals in the sun's atmosphere, has any 
hygienic effect upon the physical organism 
as the result of the therapeutic action of iron 
on the blood distributed so freely through 
the minute capillary vessels ramifying on 
the surface of the body ? In the absence of 
any hypothesis of a more satisfactory cha- 
racter to account for the beneficial action of 
light, it is reasonable to suppose that the 
iron vapour detected in the sun's beam may 
have a physiological as well as a mechanical 
effect upon the composition of the blood 
by throwing into the general circulation, 
through the vessels of the skin, a most 
important vital constituent.* 

In the present state of our knowledge it 
is impossible to dogmatise on this subject. 



* There does not appear to be anything improbable in 
this hypothesis ? when we consider that mercury may be made 



278 On the Influence of Light. 

The matter in review must still be considered 
sub judice, and purely speculative^ and until 
further experiments are made it is wise to 
hold in reserve any theory that may have 
been formed in relation to it. 



to affect the system by subjecting the patient to its influ- 
ence in the form of a vapour-bath, the mercury of course 
being absorbed principally by the skin, although a portion 
may pass into the lungs. That persons handling the soluble 
salts of lead are often poisoned in consequence of the 
metal passing through the integuments is a generally ad- 
mitted fact. 

Dr. Th. Clemens, of Frankfort-on-the-Maine (Deutsche 
Klinik, 1865-6, Schmidt's Jahrbucher, 1866), has "ob- 
served the immunity from cholera of coppersmiths. Hence 
he recommends as a cholera disinfectant a spirit of chlorate 
of copper, and advises the same preparation to be used 
both internally and externally upon the skin as an actual 
preservative." — Half-yearly Abstract, 1866, p. 5. 



279 



APPENDIX. 



I. THE BLESSINGS OF LIGHT : MILTON S BLINDNESS. 

II. SUGGESTIONS FOR THE REGULATION OF LIGHT 
IN DARK ROOMS, ETC. 

III. THEORIES OF LIGHT. 

IV. EFFECT OF LIGHT ON THE SKIN. 
V. THE SUN. 

VI. NUTRITION OF PLANTS. 

VII. VITALITY OF SEEDS. 

VIII. THE MOON. 

IX. ANIMALS INFLUENCED BY THE STATE OF THE 
WEATHER. 

X. ON THE DISTRIBUTION OF LIGHT BY ARTIFICIAL 
MEANS. 

XI. ADVANTAGES OF LIGHT IN THE TREATMENT OF 
THE SICK. 

XII. ON THE REGULATION OF THE QUANTITY OF 
LIGHT ADMITTED INTO THE CHAMBERS OF 
THE SICK. 



Appendix. 281 



THE BLESSINGS OF LIGHT: MILTON'S 
BLINDNESS. 

(Vide Preface.) 

In the subjoined lines Milton alludes with touching 
pathos to his own sad deprivation of sight : — 

" Thus with the year 
Seasons return, but not to' me returns 
Day, or the sweet approach of eve or morn, 
Or sight of vernal bloom, or summer's rose, 
Or flocks, or herds, or human face divine j 
But cloud instead, and ever-during dark 
Surrounds me, from the cheerful ways of men 
Cut off, and for the book of knowledge fair 
Presented with an universal blank 
Of Nature's works, to me expunged and rased, 
And knowledge at one entrance quite shut out." 

I append to the preceding affecting wail of dis- 
tress a copy of a posthumous poem (having reference 
to his blindness) sold to have been written by 
Milton. I have not been able to ascertain at what 
period these lines were penned ; bat, assuming them 
to be genuine, I should suppose they were written 
long subsequently to the verses previously quoted. 
They are deeply interesting, as showing the state of 



282 Appendix. 



Milton's feelings with regard to his infirmity at 
different epochs of his life : — 

1. 

" I am old and blind ! 
Men point at me as smitten by God's frown ; 
Afflicted and deserted of my mind — 
Yet I am not cast down. 

11. 

" I am weak, yet strong ; 
I murmur not that I no longer see — 
Poor, old, and helpless, I the more belong, 
Father Supreme ! to Thee. 

hi. 

" O merciful One ! 
When men are farthest, then Thou art most near ; 
When friends pass by, my weakness shun, 
Thy chariot I hear. 

iv. 

" Thy glorious Face 
Is bending towards me, and its holy light 
Shines in upon my lonely dwelling-place, 
And there is no more night. 



Appendix. 283 



" On my bended knee 
I recognise Thy purpose clearly shown : 
My vision Thou hast dimmed, that I may see 
Thyself — Thyself alone. 



VI. 

" I have naught to fear ; 
This darkness is the shadow of Thy wing -, 
Beneath it I am almost sacred — here 
Can come no evil thing. 



VII. 

" O ! I seem to stand 
Trembling where foot of mortal ne'er hath been, 
Wrapped in the radiance of that sinless land, 
Which eye hath never seen. 



VIII. 

" It is nothing now : 
When heaven is op'ning on my sightless eyes, 
Soft airs from Paradise refresh my brow, — 
The earth in darkness lies. 



284 Appendix. 



IX. 

" Visions come and go ; 
Shapes of resplendent beauty round me throng j 
From angel lips I seem to hear the flow 
Of soft and holy song. 

x» 

" In a purer clime 
My being fills with rapture — waves of thought 
Roll in upon my spirit — strains sublime 
Break over me unsought. 

XI. 

" Give me now my lyre ! 
I feel the stirrings of a gift divine ; 
Within my bosom glows unearthly fire, 
Lit by no skill of mine." 



appendix. 285 



SUGGESTIONS FOR THE REGULATION OF 
LIGHT IN DARK ROOMS. 

(P- 70 

" In all great towns, where neither houses nor 
palaces can be insulated, there are almost in every 
edifice dark and gloomy crypts thirsting for light ; 
and in the city of London there are places of busi- 
ness where the light of day never enters, and where 
the precious light which the sky sends down be- 
tween chimney-tops is allowed to fall useless on the 
ground. On visiting a friend whose duty confined 
him to his desk during the official part of the day, 
we found him with bleared eyes struggling against 
the feeble light which the opposite wall threw into 
his window. We counselled him to extend a blind 
of fine white muslin on the outside of his window, 
and flush with the wall. The experiment was soon 
made. The light of the sky above was caught by 
the fibres of the linen, and thrown straight upon his 
writing-table, as if it had been reflected from an 
equal surface of ground glass. We may mention 
another case equally illustrative of our process. A 
party visiting the mausoleum of a Scottish nobleman 
wished to see the gilded receptacles of the dead 
which occupied its interior. There was only one 



286 Appendix. 



small window through which the light entered, but 
it did not fall upon the objects to be examined. 
Upon stretching a muslin handkerchief from its four 
corners, it threw such a quantity of light into the 
crypt as to display fully its contents." 

Sir D. Brewster. 



THEORIES OF LIGHT. 

I have referred to the two theories that have pre- 
vailed in the scientific world regarding the nature 
and propagation of light — viz., the corpuscular 
theory of the immortal Newton, and the undulatory 
theory of Huygens, afterwards revived and fully 
elaborated by Dr. Young. Sir Isaac Newton sup- 
posed that light was composed of particles of ex- 
cessive minuteness, which were projected from the 
luminous body with a velocity equal to 193,000 
miles in a second. The undulatory theory was 
based upon the hypothesis, that light was trans- 
mitted from its source by vibrations or undulations 
of an ethereal fluid of great elasticity in spherical 
superficies in the form of waves, similar to the 
transmission of sound. 



Appendix, 287 



The principles of the undulatory theory are thus 
stated by Sir J. Herschel : — ■ 

1. That an excessively rare, subtle, and elastic 
medium, or ether, fills all space, and pervades all 
material bodies, occupying the intervals between 
their molecules ; and either by passing freely among 
them, or by its extreme rarity, offering no resistance 
to the motion of the earth, the planets, or comets 
in their orbits, appreciable by the most delicate 
astronomical observations, and having inertia, but 
not gravity. 

2. That the molecules of the ether are susceptible 
of being set in motion by the agitation of the par- 
ticles of ponderable matter ; and that when any one 
is thus set in motion it communicates a similar 
motion to those adjacent to it, and thus the motion 
is propagated farther and farther in all directions, 
according to the same mechanical laws which regu- 
late the propagation of undulations in other elastic, 
media, as air, water, or solids, according to their 
respective constitutions. 

3. That in the interior of refracting media the 
ether exists in a state of less elasticity, compared 
with its density, than in vacuo {i.e., in space empty 
of all other matter) 5 and that the more refractive 
the medium, the less, relatively speaking, is the 
elasticity of the ether in its interior. 



288 Appendix. 



4. That vibrations communicated to the ether in 
free space are propagated through refractive media 
by means of the ether in their interior, but with 
a velocity corresponding to its inferior degree of 
elasticity. 

5. That when regular vibratory motions of a 
proper kind are propagated through the ether, and, 
passing through our eyes, reach and agitate the 
nerves of our retina, they produce in us the sensa- 
tion of light in a manner bearing a more or less 
close analog}' to that in which the vibrations of 
the air affect our auditory nerves with that of 
sound. 

6. That as, in the doctrine of sound, the fre- 
quency of the aerial pulses, or the number of 
excursions to and fro, from the point of rest made 
by each molecule of the air, determines the pitch, 
or note ; so, in the theory of light, the frequency 
of the pulses, or number of impulses made on our 
nerves in a given time by the ethereal molecules 
next in contact with them, determines the colour 
of the light ; and that as the absolute extent of the 
motion to and fro of the particles of air determines 
the loudness of the sound, so the amplitude or extent 
of the excursions of the ethereal molecules from 
their points of rest determines the brightness or 
intensity of the light. — Dictionary of Science, Lite- 



Appendix. 289 



rature, and Art. By W. T. Brande, D.C.L., 
F.R.S. L. & E. 



EFFECT OF LIGHT ON THE SKIN. 
(P. 20.) 

" Amongst the carpenters I noticed one with a 
remarkable staining of the skin, some portions of 
his face and neck being intensely bronzed, while 
other parts remained quite fair, giving the man a 
very unsightly mottled appearance. In plain terms, 
he was enormously freckled, the stained skin being 
about the average colour of the faces of the artisan 
and labouring classes in the north of China. His 
disfigurement, consequently, arose from the refusal 
of the whole of the exposed portions of his body 
equally to take on the bronzing process. I made 
him show me his skin where habitually protected 
from the sun, and it was as fair as an European's." — 
Peking and the Pekingese. By D. F. Rennie, M.D. 
London. 1865. 



U 



290 Appendix. 



THE SUN. 
(P. 68.) 

" The sun 
Had first his precept so to move, so shine, 
As might affect the earth with cold and heat 
Scarce tolerable, and from the north to call 
Decrepit winter, from the south to bring 
Solstitial summer's heat. To the blank moon 
Her office they prescribed ; to the winds they set 
Their corners, when with bluster to confound 
Sea, air, and shore 5 the thunder when to roll 
With terror through the dark aerial ball. . . . 
Beast now with beast gave war, and fowl with fowl, 
And fish with fish : to graze the herb all leaving, 
Devoured each other, nor stood much in awe 
Of man, but fled him, or with countenance grim 
Glared on him passing." — Milton. 

" The sun's rays are the ultimate source of almost 
every motion which takes place on the surface of the 
earth. By its heat are produced all winds, and those 
disturbances in the electric equilibrium of the atmo- 
sphere which give rise to the phenomena of light- 
ning -, and probably, also, to those of terrestrial 
magnetism and the aurora. By their vivifying 



appendix. 291 



action vegetables are enabled to draw support from 
inorganic matter, and become, in their turn, the 
support of animals and. of man, and the sources of 
those great deposits of dynamical efficiency which 
are laid up for human use in our coal strata. By 
them the waters of the sea are made to circulate in 
vapour through the air, and irrigate the land, pro- 
ducing springs and rivers. By them are produced 
all disturbances of the chemical equilibrium of the 
elements of nature, which, by a series of composi- 
tions and decompositions, give rise to new products, 
and originate a transfer of materials. Even the 
slow degradation of the solid constituents of the 
surface, in which its chief geological changes con- 
sist, is almost entirely due, on the one hand, to the 
abrasion of wind and rain, and the alternation of 
heat and frost ; on the other, to the continual beat- 
ing of the sea waves, agitated by winds, the results 
of solar radiation. Tidal action (itself partly due 
to the sun's agency) exercises here a comparatively 
slight influence. The effect of oceanic currents 
(mainly originating in that influence), though slight 
in abrasion, is powerful in diffusing and transporting 
the matter abraded 5 and when we consider the im- 
mense transfer of matter so produced, the increase 
of pressure over large spaces in the bed of the ocean, 
and diminution over corresponding portions of the 
V 2, 



292 appendix. 



land, we are not at a loss to perceive how the elastic 
power of subterranean fires, thus repressed on the 
one hand, and relieved on the other, may break 
forth in points when the resistance is barely adequate 
to their retention, and thus bring the phenomena of 
even volcanic activity under the general law of solar 
influence. 

" The great mystery, however, is to conceive how 
so enormous a conflagration (if such it be) can be 
kept up. Every discovery in chemical science here 
leaves us completely at a loss, or rather, seems to 
remove farther the prospect of probable explana- 
tion. If conjecture might be hazarded, we should 
look rather to the known possibility of an indefinite 
generation of heat by friction, or to its excitement 
by the electric discharge, than to any actual com- 
bustion of ponderable fuel, whether solid or gaseous, 
for the origin of the solar radiation." — Good Words. 



Appendix. 293 



NUTRITION OF PLANTS. 

(P- 79-) 

" Since the sun-light is composed of many dif- 
ferently coloured rays and different principles, it 
becomes an interesting inquiry which of these is the 
immediate agent in ministering to the nutrition of 
plants. In 1843, by causing plants to effect the 
decomposition of carbonic acid in the prismatic 
spectrum, I found that the yellow is by far the 
most effective, the relative powers of the various 
colours being as follows: — 1, yellow 3 2, green; 
3, orange; 4, red; 3, blue; 6, indigo; 7, violet." 
— Draper. 



VITALITY OF SEEDS. 

(P. 79-) 

It has been a question with botanists how to 
account for the longevity or vitality of seeds : T 
refer particularly to wheat, which has been found 
in Egyptian sarcophagi, proved to be many thousand 
years old. These seeds, when put into the ground, 
have fully germinated, and been most produclive. 
The persistent vitality of such seeds, according to 



294 Appendix. 



the best botanical authorities, depends upon three 
principal conditions, viz. : i, uniformity of tem- 
perature ; 2, moderate dryness j and 3, the exclu- 
sion of light. Seeds brought from India (says Dr. 
Lindley) round by the Cape of Good Hope rarely 
vegetate freely. This he says is owing to the 
double exposure to the heat of the equator, and 
the subsequent arrival of the seeds in cold lati- 
tudes. Seeds brought overland from India, and 
not exposed to such fluctuations of temperature, 
retain their active vital principle. Seeds will travel 
with safety for many months if buried in clay 
rammed hard in boxes. Seeds of the mango are 
thus brought alive from the West Indies, as well 
as the principal part of the araucania pines which 
have been transported from Chili to England. 



THE MOON. 
(P. 89.) 

The moon appears to have called forth the fire 
and sublimity of poetic genius in all ages and in 
all climes. Some of the most beautiful and touch- 
ing sonnets that adorn the English language are 
addressed to the moon. I cannot forbear to quote 



Appendix. 295 



an illustration from the pen of Charlotte Smith, 
one of our most exquisite writers of sonnets, the 
immortal Milton alone excepted : — 

" Queen of the silver bow ! — by thy pale beam, 
Alone and pensive, I delight to stray, 
And watch thy shadow trembling in the stream, 
Or mark the floating clouds that cross thy way ; 
And while I gaze, thy mild and placid light 
Sheds a soft calm upon my troubled breast : 
And oft I think — fair planet of the night — 
That in thy orb the wretched may have rest j 
The sufferers of the earth, perhaps, may go — 
Released by death — to thy benignant sphere j 
And the sad children of despair and woe 
Forget in thee their cup of sorrow here. 
Oh, that I soon may reach thy world serene ! 
Poor wearied pilgrim in this toiling scene !" 

" In savage life, especially in high latitudes, the 
moon is an ever-present power. When the Red 
Indian speaks of moons as measures of time, he 
speaks in the tone of affection and reverence for 
the benign luminary that guides his steps through 
the trackless forest. The Oriental bows to the sun, 
but the Red Indian nurtures his grand and impas- 
sive nature in the mild beams of the moon. In 
hunting and trapping, the moon is his ever-faithful 



296 Appendix. 



ally, and he would as soon think of doubting its use 
as he would the use of his spear or his traps. 

" But the use of the moon is not confined to light- 
giving. As a mechanical power, the moon is of 
much service. The sun is the grand source of 
power on the face of the earth ; but still some little 
work is left for the moon. To her chiefly is as- 
signed the task of raising the tides of the ocean. 
The tides are of incalculable benefit to man. In a 
sanitary point of view, the moon may be regarded 
as the great scavenger of our globe. Twice every 
day she flushes, with sea-water in abundance, the 
rivers on which our towns are situated, and keeps 
them comparatively pure. Again, by her mechani- 
cal power, she bears ships on the crest of the tidal 
wave deep into the heart of the country, where the 
centres of commerce are often found. Insignificant 
streams are thus rendered navigable, and cities 
brought into immediate connexion with the ocean — 
the highway of commerce. By the convenience 
afforded by the moon, London is at the same time 
connected with the ocean, and in the heart of the 
country, where it can be best protected from any 
invasion. In an island of such limited extent as 
Great Britain, the rivers must necessarily be small, 
but the tidal wave compensates for the defect, and 
gives us the advantages of river navigation. The 



Appendix. 297 



mechanical power of the tide is made available by 
means of the tide-mill. The rise and fall of the 
tide can be utilized as well as the fall of the river. 
This source of power has not been very generally 
turned to account, though there is no mechanical 
difficulty in applying it." — Good Words. 



ANIMALS INFLUENCED BY THE STATE 
OF THE WEATHER. 

(P. 229.) 

Many of the diseases of animals are greatly in- 
fluenced by states of the atmosphere. It is re- 
marked that immediately before rain, and particu- 
larly before great falls of snow in winter, dogs are 
dull : their ears become inflamed, and they lie 
drowsily by the lire the principal part of the day. 
Swine are observed to be uneasy in windy weather, 
and show symptoms of restlessness even before the 
winds begin to blow by running about with a 
peculiar tossing up of the head. Hence the popular 
notion that pigs can foresee the wind. 



298 Appendix. 



ON THE DISTRIBUTION OF LIGHT BY 
ARTIFICIAL MEANS. 

(P- 237-) 

With the object of distributing light, Sir David 
Brewster suggests that " the opposite sides of the 
street or lane should be kept whitewashed with 
lime, and for the same reason the ceilings and walls 
of the apartments should be as white as possible, 
and all the furniture of the lightest colours. Having 
seen' such effects produced by imperfect means, we 
feel as if we had introduced our poor workman or 
needle-woman from a dungeon into a summer- 
house, where the aged can read their Bible, where 
the inmates can see each other, and carry on their 
work in facility and comfort." 



ADVANTAGES OF LIGHT IN THE TREAT- 
MENT OF THE SICK. 

(P- 255-) 

" Who has not observed the purifying effect of 
light, and especially of direct sunlight, upon the air 
of a room ? Here is an observation within every- 
body's experience. Go into a room where the 



appendix. 299 



shutters are always shut (in a sick-room or a bed- 
room there should never be shutters shut), and 
though the room be uninhabited, though the air 
has never been polluted by the breathing of human 
beings, you will observe a close, musty smell of 
corrupt air — of air, i.e., unpurifled by the effect of 
the sun's rays. The mustiness of dark rooms and 
corners, indeed, is proverbial. The cheerfulness of a 
room, the usefulness of light in treating disease, is 
all-important. 

" Heavy, thick, dark window or bed - curtains 
should, however, hardly ever be used for any kind 
of sick in this country. A light white curtain at the 
head of the bed is, in general, all that is necessary, 
and a green blind to the window, to be drawn down 
only when necessary. 

" ( Where there is sun there is thought.' All 
physiology goes to confirm this. Where is the 
shady side of deep valleys, there is cretinism. 
Where are cellars and the unsunned sides of narrow 
streets, there is the degeneracy and weakliness of 
the human race — mind and body equally degenerat- 
ing. Put the pale withering plant and human 
being into the sun, and, if not too far gone, each 
will recover health and spirit. 

" It is a curious thing to observe how almost all 
patients lie with their faces turned to the light, ex- 



300 appendix. 



actly as plants always make their way towards the 
light ; a patient will even complain that it gives 
him pain ' lying on that side.' ' Then why do you 
lie on that side ?' He does not know ; but we do. 
It is because it is the side towards the window. A 
fashionable physician has recently published in a 
Government report that he always turns his patients' 
faces from the light. Yes, but nature is stronger 
than fashionable physicians, and depend upon it she 
turns the faces back, and towards such light as she 
can get. Walk through the wards of a hospital, 
remember the bedsides of private patients you have 
seen, and count how many sick you ever saw lying 
with their faces towards the wall." — Notes on 
Nursing. By Florence Nightingale. 



ON THE REGULATION OF THE QUANTITY 
OF LIGHT ADMITTED INTO THE CHAM- 
BER OF THE SICK. 

(P. 2570 

" The quantity of light admitted into the sick- 
chamber is a matter of immense importance to its 
suffering occupant. As light is an element of cheer- 
fulness, it is on that account desirable that as much 



Appendix. 301 



should be admitted as the patient can bear without 
inconvenience. The light should be soft and sub- 
dued, not glaring j and care should be taken that 
bright, lustrous objects, such as crystals and looking- 
glasses, should be kept out of the patient's view, and 
that neither the name of a lamp or candle, nor its 
reflection in a mirror, be suffered to annoy him by 
flashing across his field of vision." — Ridge On 
Health and Disease. 



THE END 



LONDON : 

SAVILL AND EDWARDS, PRINTERS, CHANDOS-STREET, 

COVENT GARDEN. 



*bim 



DISORDERS OF THE MIND, DISEASES OF THE BRAIN, 

PSYCHOLOGICAL MEDICINE, AND 

THE MEDICAL JURISPRUDENCE OF INSANITY, 

By FOEBES WINSLOW, M.D. 



On the Incubation of Insanity* 

(Pamphlet.) 
ii. 

The Health of Body and Mind. 

(lVol.,8vo.) 

in. 

The Anatomy of Suicide. 

(1 Vol., 8vo.) 

IV. 

Lettsomian Lectures on Insanity. 

(1 Vol., 8vo.) 

V. 

The Plea of Insanity in Criminal 

Cases. 

(1 Vol., 12mo.) 



WORKS BY FORBES WINDOW— continued. 



ON THE 

Obscure Diseases of the Brain, and 
Disorders of the Mind. 

(Third Edition. 1 Vol., 8vo.) 



Quarterly Journal of Psychological 
Medicine and Mental Pathology. 

(8vo.) 
(Seventeen Annual Volumes of this Work have been published.) 



VIII. 

On Uncontrollable Drunkenness, 

CONSIDEBED AS A. TOEM OF 

Mental Disorder. 

ETC. ETC. 

(Pamphlet.) 



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